By Enda Brady, Sky News Correspondent
Olympic and Paralympic champions have voiced their dismay at news that the stadium may not open fully until the summer of 2016.
Four bids are still being considered as full-time tenants at the Stratford venue, but each bid will require significant and time-consuming modifications.
Dennis Hone, chief executive of the London Legacy Development Committee, revealed this week that it will not re-open until August 2015 at the earliest and probably not before August 2016.
Olympic champion Jessica Ennis told Sky News that it is important the stadium is opened to the public as soon as possible.
She said: "I've some amazing memories of the stadium, like a lot of other athletes.
"I'd love to see it opened to the public as soon as possible."
Leyton Orient FC are among four bidders to use the stadium in Stratford Paralympic double gold medallist Hannah Cockroft said it is vital to speed up the process so that the goodwill generated by the success of London 2012 could be tapped into.
She said: "The danger is that if it's not opened fully to the public for four years then that interest will wane.
"It's an amazing venue and people want to see it, they want to be a part of it. I really hope they sort this out, they have to."
A transformation project costing nearly £300m is currently under way at the site and is expected to last up to 18 months.
The park itself will be opened to the public on July 27 next year, one year to the day the Games opened in London.
Maria Miller, Secretary of State for Culture, Media and Sport, told Sky News: "The stadium is vital for the legacy of the Games, but the important thing is to get the right tenant in."
The four bidders are West Ham United FC, Leyton Orient FC, a Formula One venture and the University College of Football Business, an academic institution owned and run by Burnley FC.
A final decision is expected in the first half of 2013, or possibly sooner.
The NHS is looking to increase volunteers at hospitals
Malala with her father at the Queen Elizabeth Hospital
Malala, seen before the attack, blogged about life under the Taliban
A protest in Pakistan against the attack on Malala Yousafzai
An ash sapling infected with the disease
Ash dieback has been found at 115 sites in the UK
Some of these ash saplings in Suffolk are infected with the disease
Soldiers scour the area in the aftermath of the Provisional IRA attack
Sellafield's radioactive waste could fill 27 Olympic swiimming pools
'It's been an absolute nightmare,' says Atiya's mother
How missing girl Atiya Anjum-Wilkinson might look at 4-5 years of age. 