Companies contracted to build the venues for the 2008 Olympic Games will deliver on their commitments despite rising costs, officials said on Wednesday.

Xu Bo, deputy director of the Beijing "Project 2008" office, admitted that rising costs were a problem for some constructors, but said the Beijing municipal government and the local Olympic organizing committee are confident that all competition venues for the Games will be in place by the end of this year as planned.

"We are strengthening the supervision and regulation in terms of the venue construction here in Beijing," Xu told a press conference Wednesday.

"The actual expenses are a little bit higher than some construction companies expected at the very beginning of the bidding, so we keep a close watch on the latest news in this regard.

"But basically we have confidence because at the very beginning we selected constructors who were large or mid-sized companies with a very professional capacity to fulfil the projects.

"Therefore we don't have any worries in this regard."

Beijing plans to build or refurbish 31 venues in the city for the Games, which will take place from August 8-24, 2008.

Sui Zhenjiang, director of the Beijing municipal construction commission, again denied reports that Beijing planned to send the migrant workers out of the city during the Games and said whether they stayed depended on their companies.

"It's up to their corporations," he said.

"If the corporations has more work in Beijing they may stay, if not, they will go home."

Beijing municipal government has also taken measures to ensure that wages are paid by sub-contractors to the 300,000 migrant workers involved in venue construction, said Sui.

"Great importance has been attached to this issue, and construction projects have been inspected to check whether salaries have been paid or not," he said.

"There were some problems and we have already dealt with them."