The Metro board, in a controversial move, voted yesterday to reject all bids on a proposed contract to build a more than $40 million U Street subway station in Northwest Washington for the long-delayed Green Line.

Metro officials contended that the lowest bidder had failed to comply with rules governing participation in the project by minority-owned businesses, and they described the other bids as too high.

In another development, the transit authority said June 7 is the opening date for a nine-mile Northern Virginia extension of Metro's Orange Line to a Vienna terminus.

Metro's minority business regulations require that 20 percent of the work be carried out by minority-owned companies.

R. Randall Nye, a lawyer for J.A. Jones Construction Co., main partner in a venture that submitted the lowest bid on the U Street contract, denied Metro officials' allegations yesterday, saying the firm had complied with minority-business goals and would have "exceeded the 20 percent minimum."

A lawyer for S.A. Healy Co., the second-lowest bidder, said Healy should have won the contract and said the company would consider legal action. Healy's bid was $46.4 million; J.A. Jones' $42.7 million.

Metro plans to seek new bids.