British Foreign Secretary David Owen asked Secretary of State Cyrus Vance today to join Britain in using what Owen later called "every form of diplomatic pressure" to get Rhodesia to end its current attack into Mozambique.

Speaking to reporters at the North-South Dialogue on international economic cooperation here, Owen suggested that the four-day-old Rhodesian attack would "most Anglo-American peace effort on Rhodesia if the troops are not withdrawn immediately.

U.S. spokesman Hodding Carter said that the United Carter shared Britain's concern over the Rhodesian action and had sent out a number of messages to the "parties concerned." He declined to say if the United States was asking South Africa to pressure Rhodesian Prime Minister Ian Smith.

State Department spokesman John Trattner said in Washington that the United States "will be consulting with" Britain and Mozambique "about the steps we could take to bring about an end to the attack and preserve the chances for a solution to the Rhodesian problem."

[Trattner said U.S. diplomats had expressed "our strong disapproval" of the attack to Rhodesian representatives in Cape Town, South Africa. He said the incursion would have "extremely serious consequences" for a Rhodesian settlement.]

[British Minister of State Ted Rowlands, who is visiting Washington, called the Rhodesian forces" presence in Mozambique "an extremely provocative act" that could make the task of finding a settlement "much greater." He added, however, that "we are not going to be deflected."]

Owen, in his remarks to reporters appealed to the South Africa government to "make it utterly clear to Mr. Smith that this sort of action is intolerable and that they will disassociate themselves from it."

South Africa's defiance of U.N. economic sanctions against Rhodesia is a vital element of survival for Smith's government.

The seizure of the Mozambique town of Mapai "must call in question the whole sincerity of the Smith regime's intention to have a peaceful transition to majority rule in 1978." Owen said, nothing that Smith had been discussing such a transition with British and American diplomats in Salisbury.

News agencies reported the following from Africa :

The Rhodesian military command in Salisbury said its troops had a "brief contact" with nationalist guerrillas a few miles northeast of Mapai.

In Maputo, the government of Mozambique said there had been heavy fighting near Mapai.