Despite objections from the United States, the 12-nation European Community is expected to give diplomatic recognition to Vietnam as a prelude to expanding trade with the communist country, a spokeswoman for the European group disclosed.

The United States has urged the influential economic and trade group to withhold recognition as long as Vietnamese troops remain in neighboring Cambodia, according to a confidential State Department cable obtained by United Press International.The Oct. 8 cable quoted an American diplomat in Brussels as telling the Belgium-based group that recognition "would send the wrong political signals."

Ella Krucoff, the Washington-based spokeswoman for the European Community, said Friday that she "expected" the group's council of ministers to approve recognition "at some point in the near future." The council meets Monday and Tuesday in Brussels.

The organization's executive commission, which includes representatives from Great Britain, France, West Germany and Italy, has recommended recognition "as a precursor to expanding trade and economic relations with Vietnam," Krucoff said.

"Unlike the United States, the commission does not see diplomatic recognition as a political statement," she said.

A State Department official confirmed that "we have made our feelings known to the Europeans. Recognition

of Vietnam would break up the framework of worldwide isolation we've tried to create. It could slow down Vietnam's troop withdrawal."

Vietnam has promised to end its 10-year occupation of Cambodia by 1990. Although Vietnam said it would remove 50,000 of its 120,000 troops by the end of this year, State Department officials say it is unlikely to come close to meeting that goal.

Vietnam has been concerned that the vacuum left in Cambodia by its troop withdrawal would be filled by the Khmer Rouge, which presided over the killing of more than a million civilians during its reign in the mid-1970s.

The U.S. position on recognition of Vietnam is supported by the six members of the Association of South East Asian Nations.