By Richard Galpin BBC correspondent in Athens

The Olympic Stadium in Athens is still under construction

Senior officials from the International Olympic Committee are starting a major inspection of preparations for next year's Olympic Games in the Greek capital, Athens.

Despite earlier fears many of the venues would not be ready in time, the IOC says it is now happy with progress.

However it is warning there is not a minute to lose.

Over the next three days the IOC delegation will hold a series of meetings with the Athens organising committee, as well as senior members of the Greek Government.

They will also tour the main sports venues, a third of which have now been completed.

Volunteer boost

Although the IOC is being more upbeat about the prospect of most things being ready in time, there are still areas of concern.

In particular, there are fears about two important public transport projects which have fallen way behind schedule.

One is for a new railway line linking the international airport with the main Olympic Stadium and city centre.

There are also worries about whether the spectacular roof for the main stadium will be completed soon enough.

The IOC clearly intends to maintain pressure on the Greek authorities to ensure no more time is wasted.

On a more positive note, a spokesman highlighted the huge number of people who have offered to be volunteers at the games.

At the latest count, 120,000, double the required number, have offered their services.

The IOC is also pleased with the sale of tickets so far, which a spokesman said was ahead of expectations.