IAAF President Lamine Diack on Thursday issued his strongest criticism yet a proposal to tear down London's Olympic Stadium after the 2012 Summer Games and replace it with a soccer venue with no running track, calling it "outrageous."

Premier League clubs Tottenham and West Ham are bidding to use the stadium site after the Olympics, but only West Ham would keep the track used for athletics. Tottenham wants to level the stadium and build a new soccer-specific venue.

The teams' proposals were put in doubt Thursday when the Olympic Park Legacy Company told The Associated Press it could still go ahead with its original plan to downsize the stadium to a 25,000-seat athletics venue if neither bid was deemed "viable."

Diack then reiterated his criticism of the plans and urged London organizers to stick to their original promise.

"To now demolish the Olympic stadium, throwing away the original 500-million-pound investment of public money seems to me an outrageous proposition, especially in the present world economic climate," Diack said in a statement. "Instead, let us keep London's promise alive and leave an athletics legacy at the venue with a top football club as a valued partner."

Both Tottenham and West Ham must submit their final plans for the stadium to the Olympic Park Legacy Company on Friday. West Ham's plan involves rebuilding the stadium and reducing seating from 80,000 to 60,000, while keeping the running track.

If the OPLC board rejects the soccer team bids, it would have to reopen the search for a tenant. The 25,000-seat design is the only option that already has planning permission.

Diack said the pledge to maintain the $853 million stadium, which is still being constructed, as an athletics venue was part of the reason London was awarded the games.

"This promise was not a footnote of London's bid — it was a core policy of their presentation to convince the Olympic family of their exciting, viable legacy plans," he said. "There is no doubt that this commitment played its part in the UK winning the right to host the 2012 games."

Tottenham's plans have angered both its own supporters, who are unhappy that the club would be moving from north to east London, and track stars, including Olympic champion Usain Bolt.

West Ham, meanwhile, is currently at the bottom of the Premier League and facing a costly relegation to the League Championship.

Former British Olympic Association chief executive Simon Clegg has said the stadium is unsuitable for both athletics and soccer. Tottenham has produced documents showing that having a running track around the field would hamper fans' ability to see action during soccer matches, while raising questions about West Ham's ability to fill a 60,000-seat stadium if the team is relegated.

Under the original 25,000-seat design, the stadium couldn't host a world athletics championships, but the flexible design would allow the capacity could be temporarily increased.

The initial plan was for the stadium to also house a secondary school for about 500 students, the National Skills Academy for sports and leisure industries, and the English Institute of Sport.

Those plans were criticized in 2009 by the London Development Agency, which warned that the 25,000-seat stadium could become a white elephant "without a credible anchor tenant."