The government of Lesotho has told the United Nations and "friendly countries" that it intends to expel up to 3,000 black South African refugees because it can no longer withstand South Africa's military and economic pressures.

Although Lesotho Foreign Minister Evaristus R. Sekhonyana said the decision to "evacuate" the refugees was not yet final, he said his government is facing "what I would characterize as an ultimatum" from South Africa to expel them. Unless "something is done to help," he said, Lesotho "has no choice. This country is being suffocated."

In Washington, the State Department and the representative of the Office of the U.N. High Commissioner for Refugees confirmed that they had been asked by Lesotho to help relocate the refugees in other countries.

South Africa, which surrounds the small black African country, contends that the refugees are activists of the revolutionary African National Congress, which is trying to overthrow the white minority government in Pretoria. Lesotho denies this, saying that it gives sanctuary only to genuine refugees from South Africa's system of strict racial segregation, called apartheid.

Last December South Africa made a military raid on what it claimed were African National Congress bases in Maseru, the Lesotho capital, killing 42 people who both the Lesotho government and the nationalist organization said were either refugees or local citizens.

Since then, South Africa has imposed increasing economic pressures. Lesotho is totally dependent on South Africa for all of its imports and exports, for supplies of fresh produce and for the employment of more than half its breadwinners as migrant workers in South Africa's mines and industries.

Following two insurgent bombings in Pretoria and Bloemfontein in May, South Africa slowed traffic crossing all border posts into Lesotho for what it said were security checks.

The resulting long lines caused shortages of essential supplies in Lesotho and brought a meeting between Sekhonyana and South African Foreign Minister Pik Botha in Johannesburg June 3. The meeting ended with a statement in which both governments agreed that neither should support elements involved in subversion against the other.

This referred to Lesotho's charge, denied by Pretoria, that South Africa supports rebel forces trying to overthrow the Lesotho government of Prime Minister Leabua Jonathan.

South Africa later ended the border slowdown, but reactivated it in mid-July when Botha complained that Lesotho was doing nothing to implement the joint declaration and also had unjustifiably arrested a South African policeman who had gone to Lesotho to coach a soccer team.

The policeman was later released, but South Africa continued stopping all but the handful of Lesotho citizens who have multiple entry visas from crossing the border. This struck at the heart of the Lesotho economy by blocking the flow of migrant workers.

Sekhonyana said by telephone tonight that South African ports also had embargoed imports to Lesotho of weapons from the United States and Britain, which he said were needed to counter an increasingly threatening insurgency against the government.

Sekhonyana said that this "strangulation" had forced his government to seek another meeting with South Africa, held yesterday in Pretoria. That meeting ended with a terse joint statement saying both governments had exchanged views on how to implement the principles agreed on at the June 3 meeting.

Yesterday's meeting included security chiefs and Foreign Ministry officials with no political leaders present.

South African officials today declined to expand on the joint statement in response to questions, and Botha said he would have no comment on Lesotho's statements on the refugees.

In Washington, Lesotho's ambassador to the United States, M'Alineo Tau, said Lesotho is engaged in a diplomatic effort to inform friendly governments that South African "persecution" was forcing it to "evacuate" between 2,000 and 3,000 refugees to other countries.

"We are asking all friendly countries to help by accepting refugees," Tau said, mentioning that the United States, Britain, Canada, West Germany and Sandinavian countries have been approached. Tau said the Office of the U.N. High Commissioner for Refugees and the U.N. secretary general had also been informed of the decision, which she said had been made the last week in July.

She said officials of Lesotho's Foreign Ministry will meet with Oliver Tambo, the African National Congress' president in exile, to explain the decision.

Asked whether the Lesotho decision was a victory for South African pressure, Tau said, "One would not be able to escape the conclusion that Lesotho caved in to South African pressure."

An administration official in Washington said the United States was told Aug. 4 of Lesotho's decision to remove the refugees. The official said the United States assumed most of the refugees would go to other African countries, but declined comment on whether the United States would accept any of them.

The Washington representative of the U.N. refugee commission, George Gordon-Lennox, said Lesotho had contacted the organization's Geneva headquarters and the U.N. secretary general with a request to settle between 1,500 and 2,000 South African refugees who are registered with the commission.

"I cannot tell you at this stage what we are going to be able to do," Gordon-Lennox said. He said the Geneva headquarters was "in a crisis meeting at the moment trying to hammer out a position."

Despite the seemingly conclusive nature of the messages reaching Washington, Sekhonyana was insistent that the Lesotho government had not yet made a final decision and was still hoping major powers would intervene to persuade South Africa to drop its demands.

He said Lesotho had asked South Africa to clarify what categories of people it was demanding should leave, and the final Cabinet decision would be made only when the information was received.

"But unless some kind of pressure can be brought to bear on South Africa there is nothing we can do," Sekhonyana added. "We will have to comply with the demands. Lesotho has no options."