Construction budgets for the new 2.5 million-square-foot Washington Convention Center at Mount Vernon Square have increased for the third time, bringing the total expected cost to $833.9 million, about17 percent more than the original estimate, center officials said this week.

The Washington Convention Center Authority's board of directors unanimously approved the increased budget in a conference call on Wednesday.

The increase was attributed to higher labor costs and the purchase of additional steel for the center's external walls.

The authority's board said there is "plenty of money" to pay for the additional costs. There is about $839.5 million budgeted for the project and an additional $90 million in reserves from revenue from the city's hotel and restaurant taxes.

"We're confident that this is going to get us to the finish line," said Lewis H. Dawley III, general manager of the authority. The center is scheduled to be finished by March 31.

Most of the money for the project comes from about $500 million in bonds backed by city hotel and restaurant taxes. The rest comes from city and federal grants and from contracts with vendors that will do business in the new center.

The estimated cost of the convention center now has increased three times. It was originally expected in 1998 to cost $714 million. The estimate rose to $756 million in December 2000. Last year, the estimate was at $799.5 million.

"The costs have gone up because we needed additional manpower. There were increases because of design changes, and it cost more to coordinate and build certain parts of the building," said Allen Y. Lew, managing director of development for the convention center.