Britain sharply attacked Nigeria's nationalization of British oil interests today and said it was likely to set back efforts to reach a settlement to the Rhodesian independent issue.

Nigeria's dramatic action last night, designed to prevent Britain from lifting economic sanctions against Rhodesia, overshadowed today's opening of the 41-nation Commonwealth conference where Britain and Africa are locked in a test of wells over southern Africa.

The use of the oil weapon by Africa's largest and most powerful state marks a new phase in the protracted dispute about Rhodesia.

British FOREIGN Secretary Lord Carrington said Nigeria's nationalization of british Petroleum's $150 million, 20 percent interest in a joint oil production company "will have a serious effect on Anglo-Nigerian relations."

"Nothing could be more counterproductive and less likely to succeed than an attempt of this kind to move the government's policy on southern africa," he said.

Carringon also sharply put Britain's objections before Maj. Gen. H.E.O. Adefope, the Nigerian foreign minister and head of its delegation, during a reception for the conference attended by hundreds of diplomats and reports.

Adefope declined to link specifically the nationalization to the Rhodesia issue but told reporters: "We must get Britain to look at Zimbabwe [the African name for Rhodesia] in a more realistic light."

The Nigerians have been annoyed by the intention of the Conservative British government of Prime Minister Margaret Thatcher to lift economic sanctions against the newly elected, block-led government of Zimbabwe Rhodesia. Such a move would help strength the government, which is opposed by all Affrican nations.

Thatcher, in her speech to the opening session of the conference of former British colonies, also criticized the Negerian move, although not directly naming Nigeria. She added a phrase to the advance text of her speech attacking a "recent sudden, arbitrary action which will affect the oil market and prices."

Thatcher, surrounded by hostile critics of her Rhodesia policy, told the conference that she is seeking a solution that would gain wide international acceptance.

"Britain is wholly committed to black majority rule," she said, making no reference to her hopes to lift economic sanctions. In apparent deference to her African critics, she noticeably avoided using the name Zimbabwe-Rhodesia that the new government has adopted.

British officials say their intention is to complete their months of consultations on the Rhodesian issue at the conference and then come up with new proposals soon for a Rhodesian settlement that would bring about wider international acceptance.

Thatcher moved further in this direction today, according to some diplomats, by making a specific reference to Commonwealth approval. There are 13 African members of the organization.

She said, "The aim is to bring Rhodesia to legal independence on a basis which the Commonwealth and the international community as a whole will find acceptable."

The host president, Zambia's Kenneth Kaunda, made it clear in his opening speech that Africa thinks whites are still in control in Rhodesia despite the April election of Prime Minister Able Muzorewa.

Kaunda ran off a litany of African complaints against the "internal settlement" that brought Muzorewa to power.

"We believe Rhodesia is a British colony," he said. "Nothing has changed. Rhodesia is still in rebellion," a reference to the illegal declaration of independence in 1965 by the government of former prime minister Ian Smith.

"The elections," Kaunda said. "were illegal" and "produced an illegal and puppet government."

"Power was not transferred to the majority in Zimbabwe," he added. "What we have in Salisbury today is white power clad in black habiliments."

Australia's Prime Minister Malcolm Fraser, seeking to play a mediating role between Britain and Africa, said the "election had created conditions for movement but in itself it has changed nothing," adding that further changes are necessary.

After this morning's open session the Commonwealth leaders will hold the rest of their informal discussions in private. They are scheduled to discuss a variety of topics including general economic problems and the Indochinese refugee situation.

The embattled Thatcher, labeled a "racist" by the Zambian press and virtually mobbed b the press on her arrival Monday night, was the center of attention as the conference opened.

The ironies of the occasion were many. Thatcher, wearing a simple print dress, was the only woman surrounded by 40 men in attire ranging from flowing African robes, including one off-the-shoulder, to Mao jackets and Western business suits. Although several of the leaders come from the military the eschewed uniforms.

Four rows behind Thatcher sat Joshua Nkomo, the guerrilla leader whosn forces are fighting in Rhodesia and whom Thatcher has labeled a "terrorist," much to Africa's annoyance, where he is regarded as a "freedom fighter."

On the other side of the room sitting behind a bouguet of flowers was Thatcher's husband Dennis, along with 13 wives who accompained the leaders. CAPTION: Picture, Prime Minister Thatcher delivers her speech at the Commonwealth conference. UPI