IOC inspector Denis Oswald has warned organisers of the Athens Olympics there can be no let up in the hectic pace of Games preparations because meeting deadlines is still in the balance.

With the 200-day countdown to the August 13-29 Games starting on Sunday, Oswald, the International Olympic Committee member in charge of the event, said much work remained to be done.

"The deadline of August 13 looms larger by the day," Oswald said in a statement at the end of of the first day of a two-day visit on Wednesday.

"It is vital that current completion dates be respected."

The biggest race -- and concern -- is to finish a landmark glass and steel roof over the main stadium.

Designed by famed Spanish architect Santiago Calatravato, the roof has been promised to be ready by May in time to do landscaping work around the stadium.

Other projects causing concern are completing a new subway system, a 20 mile suburban railway that would also run to Athens new airport and a 15 mile tramway system that would open central Athens to the sea.

"There is no time to take our eyes off the ball; this match is far from being over," Oswald said.

Greece's preparations for the Games fell far behind schedule in their early years because of political infighting.

But in the past year the IOC has praised organisers for stepping up the pace of work to an extent where it now goes on virtually around the clock, whatever the weather.

Oswald said in meetings with leaders of Greece's main political parties -- the governing PASOK socialist party and the conservative New Democracy party -- he received assurances that a March 7 general election would not disrupt preparations.

The conservatives lead in opinion polls going into the election raising the prospect of a new government taking charge of the country just five months before the Games.