Six weeks of talks on improving East-West contacts ended today with the United States defending its veto of a compromise final document and with other western delegates seeking to minimize the split the U.S. action has opened in the Atlantic alliance.

The proposed compromise, drafted by neutral and nonaligned countries in the hope of breaking a deadlock, dealt with reunifying divided families and with improving conditions for other personal contacts. The Soviet Union, the other East Bloc countries and all of the Atlantic alliance countries with the exception of the United States had indicated a willingness to approve it.

But yesterday, Michael Novak, the chief U.S. delegate, rejected it. He told the final plenary meeting of the 35 countries represented here that the proposed final document contained loopholes and was potentially dangerous.

"My government takes words seriously," Novak said today, and added, "There is unease in our country about the growing gap between words and compliance." He said that if the document had been accepted, people could have been hurt because it contained language that could be distorted by cynical governments.

Of the delegates here from other countries of the North Atlantic Treaty Organization, none supported the American veto, but all expressed at least some understanding.

Dutch Ambassador Hans Meesman said: "We were prepared to accept the outcome of our deliberations. But as we share some of the hesitations of those who felt it was inadequate, we have understanding for the inability of one of our friends and allies to join the consensus."

Yuri Kashlev, the chief Soviet delegate, criticized the U.S. rejection of the proposals as having "threatened us with a clenched fist."