DAEGU, South Korea - London and Doha will go head-to-head to host the 2017 world athletics championships, IAAF chief Lamine Diack said on Sunday.

"Barcelona is no longer a candidate," the International Association of Athletics Federations president told a news conference on the last day of the Daegu world championships. "There are only two candidates, London and Doha."

Barcelona had expressed interest in the global meeting but did not submit an official bid, IAAF spokesman Nick Davies said.

The IAAF Council will choose between London and Doha at its November meeting in Monaco.

London's chances depend on an athletics track being maintained in the 2012 Olympic Stadium.

"If they have no stadium, they have no chance," Diack told Reuters in an interview on Saturday.

Davies said British officials had assured the IAAF there would be a track in the stadium.

The bid has been clouded by a row over the Olympic Stadium, with Premier League soccer club Tottenham Hotspur seeking a judicial review of the decision to allow West Ham United to take over the facility after next year's Games. West Ham has said it would retain a track in the stadium.

Doha, in a bid to avoid some of its hottest weather, would like to hold the championships in September rather than the traditional August date. The IAAF will consider the request in the coming weeks.

"It is possible that a date can vary," Diack said, noting there was no fast rule the championships must be in August.

"The last half of September is something I have nothing against," he said.

The Daegu championships began on Aug 27 and end later on Sunday. Moscow will hold the event in 2013 and Beijing in 2015.

Diack also repeated his comments that the one-and-you-are-done false start rule would not change.

The rule, in effect since 2010, gained worldwide attention when Jamaican world record holder Usain Bolt was disqualified in the 100 metres final on the championships' second day.

"But that is not going to make us change," Diack said.

IAAF officials also said these have been a clean championships with no positive doping tests reported as of mid-day Sunday.

Blood samples from 1,848 athletes, all of the accredited participants, have been collected during the championships for current and future analysis as part of a breakthrough IAAF project.

The program is in addition to in-competition testing of more than 500 urine samples.