Japan's new proposal for resolving a contentious construction trade dispute is too vague to determine whether agreement can be reached, Commerce Secretary C. William Verity officially told that nation yesterday. But he added that the plan "meets our minimum requirements" for reopening talks that broke off in November after Japanese negotiators backed away from high-level commitments.

Ambassador Nobuo Matsunaga presented the offer to Verity last week on the eve of the visit here by Japanese Prime Minister Noburo Takeshita. It was initially hailed by a senior Reagan administration official as offering a quick solution to a trade dispute in which Congress has ordered a ban on federally funded construction and engineering contracts to Japanese firms as long as Japan maintains its barriers to U.S. companies bidding on some $60 billion in planned public works projects.

Verity's letter to Matsunaga dashed Japanese hopes that their offer would be accepted. Earlier, U.S. Trade Representative Clayton K. Yeutter said that the U.S. might have to apply sanctions to force Japan to open its construction and engineering projects to foreign companies.

"Your undertaking to assure that U.S. companies can bid on certain projects directly managed by the government of Japan meets our minimum requirement for reopening the negotiations which ended last November," Verity wrote Matsunaga.

"However, the rest of the proposal leaves so many questions unanswered that it is not possible at this point to determine whether it contains all the elements necessary to resolve this problem," Verity continued.

He called for quick talks in Washington, but U.S. construction and engineering industry officials complained that the Japanese are likely to drag out the negotiations.

"Every day the status quo remains is another day that they {Japanese construction and engineering companies} increase their penetration in the U.S. market while denying access to us," said Mark Chalpin, spokesman for the International Engineering and Construction Industry Council.

The issue is one of the hardest for Japan to handle because its construction industry is politically powerful and a major contributor to members of the ruling Liberal Democratic Party.