Elite sport is crying out for clarity over the government's plans to deliver full capacity crowds at events this summer amid a flurry of confusing and contradictory messages.

Clubs and governing bodies are desperate to welcome full houses after more than a year without supporters.

Finances are stretched to the very limit, but the route back to normality remains obscure, sources have told Sportsmail, and it is still unclear when turnstiles will be fully open.

Hundreds of thousands of tickets have been sold for Britain's Great Summer of Sport, as fans clamour for a safe return after three lockdowns in 14 months, but many will have to be refunded if capacity crowds do not return.

Earlier this year, Prime Minister Boris Johnson dangled the exciting prospect of full stadiums in front of sport and its supporters when he suggested all social distancing could end from June 21, as part of the government's roadmap out of lockdown.

But in recent months mixed messages over the use of covid passports and social distancing has left sport confused about the government's intentions and its ability to deliver.

Some sources say the plans vary depending on which branch of government is speaking.

'It changes almost on a daily basis,' said one.

Covid passports have been talked up - and talked down - and now the abolition social distancing is back on the agenda as Britain's vaccine rollout continues apace.

Today, the Prime Minister told reporters: 'It also looks to me as though June 21 we'll be able to say social distancing as we currently have to do it, the one-metre plus, I think we have got a good chance of being able to dispense with the one-metre plus from June 21.'

No social distancing would suggest capacity crowds at sport could be back on, reviving the tantalising possibility of full houses for the Summer of Sport, including Test matches and T20 internationals.

However, the premier's comments, made while campaigning ahead of a byelection in Hartlepool, have no detail attached.

Furthermore, they came after Dominic Raab, the Foreign Secretary, sparked a backlash on Sunday saying something different.

He suggested social distancing and face masks may be retained beyond the end of the roadmap.

'We are not being told anything,' said a well-placed source. 'It is deeply confusing.'

'All sports are waiting,' said another frustrated insider.

Only last month, 10 sports' leaders wrote to the Prime Minister and the heads of the main opposition parties, stressing the need to test Covid passports to support the return to full capacities.

It was suggested the passports - or covid certification in government parlance - would check the vaccination status, immunity using an antibody test or confirm a person did not have the virus with a test result.

The letter, which was sent by representatives from football, rugby, tennis, motor sport and cricket, was titled: 'Sports support Covid certification (testing and vaccination) review as a credible option to enable full venues from 21 June onwards.'

And it stated: 'Looking ahead to June 21, we support the Government's ambition to secure the full return of fans, without restrictions if possible.

'Of necessity, this will depend upon the Government agreeing that it is safe to lessen or drop social distancing requirements.'

It added: 'We know that our stadia can only be fully filled with an assurance process.

'This process must ensure that everyone can access stadia and must include arrangements that would verify a negative Covid test or an antibody test or vaccination certification.'

However, after positive noises from Boris Johnson about using passports to help fans return, sports are now left wondering what is happening to hasten the comeback of spectators with the British Formula One Grand Prix at Silverstone and Betfred Rugby League Challenge Cup looming large in July.

In Israel, covid passports, known as 'green passes' are already in use at football grounds in combination with testing for coronavirus.

In the US, Major League Baseball teams are asking for covid passports to safely return crowds, including the New York Yankees, and one third of NBA basketball teams are using 'health passes' supplied by the private sector, according to CBS.

But here, there is a view among sports people that the Prime Minister was stung by a political backlash to the idea of covid certification, with opposition parties, some of his own MPs and civil rights campaigners quickly uniting against the idea.

Covid passports were surprisingly omitted from the government's Events Research Programme, which began in April and is due to conclude with the FA Cup final on May 15.

The uncertainty around covid passports - and the return of crowds as a whole - appears to be summed by vaccines minister, Nadhim Zahawi.

He has previously labelled the concept 'discriminatory', but last week he told BBC Breakfast: 'If you want to go to 100% seat capacity at Wembley, you have to look at all these technologies which are available to you and I think it is only right and responsible for any government to explore that.'

The view of many in sport remains that covid passports will still be a useful, short-term option to get bums back on seats and in short order.

Premier League executive director Bill Bush continues to push the case.

He told the All-Party Parliamentary Group on Coronavirus that top flight club's current planning was for matches with a capacity of around 18% in the absence of Covid passports.

And he added: 'We do support some form of certification for our events,'

Bush has previously painted a bleak picture of football without certification, with social distancing, no food and no away support.

Meanwhile, sport continues to count the cost of limits on crowd capacities, while struggling to make reliable plans for the future.

Bill Sweeney, chief executive of the Rugby Football Union, told Sky Sports at the weekend: 'We have had to cut back our costs... part of that was to reduce the head count - 141 positions we have identified at risk. It is very tough.'

The RFU is planning matches in October and November but is still not sure how many fans will be allowed into Twickenham, which has a capacity of 80,000, even then.

'We are working with government seeing what is the capacity of crowds we can accommodate safely here...' added Sweeney. 'But assumptions change every week.'

A DCMS spokesperson said: 'The first phase of the Events Research Programme is trialling the use of test on entry protocols, alongside a range of other safety measures, to examine how we can support the full reopening of venues.

'The results will feed into the separate wider review of Covid status certification ahead of Step 4 in the roadmap.

'We are working hard to ensure fans can safely return to full capacity events as soon as possible.'

Key events after 21 June - the earliest date all restrictions can be lifted:

11 June-11 July: Football - Euro 2020 in various countries, including seven matches at Wembley

28 June-11 July: Tennis - Wimbledon

29 June, 1 & 4 July: Cricket - England v Sri Lanka ODIs

8, 10 & 13 July: Cricket - England v Pakistan ODIs

13: Athletics - Diamond League: Anniversary Games at London Stadium

15-18 July: Golf - The Open at Royal St George's

16, 18 & 20 July: Cricket - England v Pakistan T20s

17 July: Rugby League - Challenge Cup final at Wembley

18 July: Formula 1 - British Grand Prix at Silverstone

4 Aug-14 Sept: Cricket - England v India five Test series

27 Sept-1 Oct: Cricket - Bob Willis Trophy final at Lord's

3 October: Athletics - London Marathon

9 October: Rugby League - Super League Grand Final at Old Trafford