WASHINGTON (AP) _ Threats of a lawsuit by homeless families hoping to find shelter in foreclosed houses caused the federal government to cancel a major sales promotion that was aimed at selling 15,000 houses this weekend.

Critics of the sale said it could have deprived the homeless of possible living space and would mainly benefit speculators.

The Department of Housing and Urban Development announced Wednesday it was calling off its ''coordinated national sales weekend'' after advocates for the homeless threatened legal action. The promotion was to include special advertising, open houses and other activities to push sales of more than 27,000 houses in several states which the federal government has taken over because their owners couldn't meet payments on federal housing loans.

The houses will remain on the market across the country, but local HUD offices have been told not to proceed with the planned sales effort because of the threatened lawsuit.

Roberta Youmans of the National Housing Law Project praised the action but said the group, which had threatened the lawsuit, still would pursue ways of getting more foreclosed houses into the hands of some of the three million Americans who have no place to live.

''We received calls from homeless individuals saying HUD was selling units and they couldn't get them,'' Ms. Youmans said in a telephone interview.

She said the group, which is based in Berkeley, Calif., had written HUD to object to the campaign and threaten a lawsuit. The project assists lawyers helping indigent clients with housing cases.

Ms. Youmans said many of the HUD sales result in homes being sold to speculators, and sometimes the homes themselves have been taken away from people who originally were homeless, putting them back on the streets. Others are being rented to people who are rendered homeless by the sales, she said.

She said the group first heard about a plan to sell 150 foreclosed houses in the Washington, D.C., area later this month and then discovered the planned nationwide campaign. The Washington area effort also has been stopped.

Ms. Youmans said homeless advocates plan to meet with HUD officials to discuss ways the houses can be used to decrease homelessness.

Bill Glavin, a HUD spokesman, said the sales effort was stopped ''as a result of the threat of litigation by homeless advocacy groups, since any protracted litigation could have an adverse affect on the future sales of foreclosed properties.''

He said the agency also was reviewing its programs for making the houses available to the homeless. Both lease and lease-purchase programs are available, and about 90 percent of the available houses can be purchased at a 10 percent discount by local agencies that would make them available to the homeless, HUD said in a statement.

Foreclosed government properties generally are available through bids that are to be opened on a specific date for each property.