A decision on the future of the Olympic Stadium faced fresh delays as the competition to find tenants was extended by eight weeks.
The London Legacy Development Corporation (LLDC) said it is to allow all parties that registered to receive the invitation to tender (ITT) additional time to submit a bid.
It is to allow more time to address a number of issues which have arisen since the ITT was issued in January, the LLDC said.
LLDC chief executive Andrew Altman said: "We are determined to run a process that is fair to all and delivers the best possible legacy for the Olympic Stadium.
"We have been very encouraged by the quality of the bids so far. However, a number of issues have arisen during the process and we believe it is sensible to give everyone more time so they can be addressed.
"We want to make the process as competitive as possible and extending the competition period will allow all parties that registered an initial interest in the stadium another chance to bid."
The LLDC said it has made "a number of clarifications" to the ITT in response to issues that have arisen since it was first issued in January.
Some potential bidders were put off by the original terms of the tender.
Governing body approvals, technical improvements to the stadium and the opportunity to bid for the right to exploit the stadium naming rights were among the controversial issues.
The aim is still to sign construction contracts for converting the stadium at the end of October and to reopen the venue in 2014.
"The fundamentals have not changed," Mr Altman said.
"This is a significant public asset and a 99-year lease and it is right that we take the time now to get the best possible outcome for the stadium."
In March, the LLDC, which was then operating as the Olympic Park Legacy Company (OPLC), confirmed that four bids were on the table from firms wanting to become tenants of the Olympic Stadium.
West Ham United, which won the now-disbanded process to move to the stadium in Stratford, east London, after the London 2012 Games, is one of the bidders.
West Ham United has applied for a 99-year lease of the stadium, which is reported to have cost £486 million to build.
The plan had been to start evaluating the four bids with the aim of making a decision before this summer's Games.
There had been 16 would-be bidders who had shown an interest but this had dropped to four once submissions were made in March.
The LLDC claimed it was not unhappy with the four bids but was addressing "technical issues" that had arisen.
It is hoped the extension will "make sure that there is a level playing field for all those who registered", a spokesman said.
Evaluation of bids will not now happen before the summer but the LLDC's "hard and fast" deadline is to have a contract in place by October, they said.