Olympic Delivery Authority chairman says body is working to identify necessary adjustments to the existing plan.

Jack Lemley, chairman of the Olympic Delivery Authority, has admitted there will be further changes to the proposed Olympic Park plan.

Lemley said that the ODA was working to identify necessary adjustments to the existing plan. He said: "Some venues may move around on the site."

Details of the changes are expected to be announced next month when the ODA board, whose make-up was announced last week, meets for the first time.

Lemley also admitted that getting resources, in particular materials, onto the site would be a "major programme". He said: "I do believe we can achieve this in the time. But this is a marathon and it will have to be a gold-medal performance - we all recognise that delays cost money."

Lemley's comments this morning came as Olympics minister Tessa Jowell, London mayor Ken Livingstone and LOCOG chairman Lord Sebastian Coe hosted the first inspection of London's Olympic sites by the International Olympic Committee's co-ordination commission.

Jowell hinted that costs for the Games were likely to rise as the construction project progresses. She said: "We are carrying out a review of all the costs and that will be a continuing discipline. Some costs will rise and some others will come down."

Her comments follow reports earlier in the month that the overall budget is likely to have to rise by about £2bn. There is also concern that costs will go up due to expected labour shortages and contractors adding an "Olympic levy" to tender prices to cover the risks associated with undertaking major public programmes.

As part of the IOC's visit today, it will witness the opening of London and Continental Railways' Stratford International Station, a key facility in LCR's plans for the controversial Stratford City developement and part of the £5.2bn Channel Tunnel rail link.

Other venues on the two-day tour will include the Milennium Dome, now known as the O2, which will host gymnastics, and the Olympic site itself.

The commission will not, however, visit Wembley, where much of the Games' football tournament will be played.