Top officials of the Washington Convention Center have decided to ask Mayor Marion Barry to approve an increase of more than 40 percent in the number of full-time employes at the center, as part of a supplemental budget request for an additional $800,000 this year.

Center officials said that shortly after the building opened in January they began to discover that projected personnel levels were well below what is actually needed to run the facility, and that as a result, part-time and overtime costs are much higher than anticipated.

Under the staff proposal, 39 full-time employes would be added to the current 85 at a cost of $333,700.

Fifteen of the new positions already have been approved by the mayor and the City Council for next year's budget, officials said. The center has a $7.5 million budget for the current fiscal year, which would be increased to $8.3 million if the staff proposal is granted.

At its meeting Tuesday, the center's board authorized the staff to submit the personnel request to the city budget office, which has set Friday as a deadline for supplemental budget proposals from various agencies.

However, the board withheld formally approving the request until more information could be provided.

"This is an awful lot of additional people," said board member Edwin K. Hoffman. "If it must be, fine, but I think as a board we just can't say 'yep.' " Hoffman and board Chairman Edward A. Singletary asked the staff to compare the size of the center's staff with those of convention centers in other cities.

City budget officials declined to comment on the staff proposal.

However, the center's request comes at a time when city officials have predicted a significant shortfall in revenues, and city agencies have been asked to look for possible budget cuts.

Barry is expected to send to the City Council soon an overall supplemental budget request for this year, including one for the convention center.

Also at Tuesday's meeting, the center's board approved giving center general manager George W. Demarest Jr. a $5,000 bonus for doing a "superb" job in supervising the opening of the center, and also raised his salary by $5,000, from $75,000 to $80,000.

Demarest is already making more than Barry, who draws a salary of $74,530 a year.

In a separate action, the center's board has agreed to pay $600,000 to the center's private food concessionaire for additional costs in constructing the building's kitchen, cocktail lounge and other food service facilities. The kitchen areas are still under construction.

When the board granted a 10-year exclusive food service contract to a joint venture controlled by Sportservice Corp., a Buffalo-based company, the firm agreed to construct and equip the kitchen and other food service areas for $2.4 million.

The center intends to purchase the kitchen and other equipment from Sportservice, but the City Council rejected the center's $2.4 million request earlier this year, meaning that the center does not have approval to buy the equipment.

Whatever happens to that request, the center has agreed to pay the $600,000 in additional costs because officials said the center, not Sportservice, is responsible for the increase.

Michael C. Rogers, deputy general manager, said the added costs resulted from the center's approving a more elaborate design for the food areas and a decision to have Sportservice build a more expensive cocktail lounge than was originally planned.

Under the new agreement, Sportservice would recover the $600,000 by withholding part of the fee the company pays the center either after the center receives approval to purchase the kitchen equipment or after the first 10 years of the contract.

In another personnel action, the board authorized an increase of more than 100 percent, from $35,000 to $75,000 a year, in the maximum compensation that can be paid for legal services to the law firm headed by the center's general counsel, David W. Wilmot.

Officials said the center already has spent $33,000 of the $35,000 in legal fees authorized for this year.