Much work is still needed for Athens to be ready to stage the Olympic Games in August, the International Olympic Committee said on Thursday.

But IOC chief inspector Denis Oswald said even though preparations had now turned into a race against time he was confident Athens would be ready for the Games which start on August 13.

"Less than six months before the Games there is still a lot to do," Oswald said in a progress report to a gathering of 500 delegates from 202 national Olympic committees in Athens.

"When you drive around the venues you will realise there is still a lot to do but we are confident the remaining time will be fully used and when you come back to Greece in August you will find everything ready.

"We are confident, even if the schedule and the time is very tight. I would like to stress the big effort made by the Games organisers and the Greek government."

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

Other projects causing concern are completing a new subway system, a 32km suburban railway that would also run to Athens' new airport and a 15-mile tramway system.

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

"In the beginning, preparation was a bit chaotic and difficult until (Athens Games chief) Gianna Angelopoulos took over," Oswald said.

He also singled out as a special problem for Greece the country's famed archaeological heritage which has meant that work was often stopped to preserve unearthed antiques.

"As soon as you dig you find interesting pieces of stone you need to save," Oswald said.