A British government inquiry disclosed yesterday that two major British oil companies broke the economic sanctions against Rhodesia and that the labor Party government of Harold Wilson was aware of the violations.

In fact, the report says, the Wilson government approved a "cosmetic" device to cover up the breach of the U.N. and British-backed sanctions.

The Wilson government not only agreed to the sancitions evading technique of swapping French for British oil, but also decided to keep it secret, lest British "sincerity" on encorcing the embargo be questioned the report said.

The inquiry ordered by David Owen. Labor's current foreign minister, passes no judgment on this activity, which took place in 1969. It simply records that Wilson's ministers agreed with oil company executives who contended that the flow of life-giving oil to the illegal white government in Rhodesia could not be stopped without an embargo against South Africa.

"We were under no circumstances willing to do that," the inquiry was told by George Thomson, now a peer and then commonwealth minister.

Detils of this story are buried in the body of the 503-page report drawn up by Thomas Bingham, a noted lawyer. He fully absolves the top management of British Petroleum and Shell, the two British companies that supplied Rhodesia with more than half its oil from the time it declared itself, independent in 1965 until at least 1977. He does not blamed Wilson, any minister or any civil servant for the continuing 12-year violation of the U.N. embargo and British law.

Bingham does have some muted criticism of lower level excutives in the two companies, largely for failing to have "effectively communicated" with their London chiefs about the unbroken flow of British oil.

Sanctions busting can earn a jail sentence of two years here and Bingham did write an annex entitled "Evidence of Crininal Offenses." What it contains has been deleted from the document made public yesterday. It has gone instead to the director of public prosecutions - roughly, the attorney general - who will determine whether any charges will be brought.

For nine years, successive governments here ostentatiously blockaded the Mozambique port of Beira, supposedly to cut off oil. So there is great public interest in and indignation over the revelation that British companies were, directly or indirectly, supplying oil elsewhere.

Bingham's confirmation that the government winked at the breach of the embargo comes a day after President Kenneth Kaunda of Zambia declared that "Wilson lied to me just as he lied to the world."

The Bingham inquiry never asked Wilson to tesify and does not even name him. Since he was chairman of the secret Cabinet committee on sanctions, however, it is assumed here that Thomson and other ministers aware of the breach told Wilson what was what.

Over the past 12 years, Wilso has steadily blasted the French, Portuguese and the United States for ensuring Rhodesia's unbroken supply of oil.

The report tells this story: When sanctions were first declared, companies jointly owned by Shell and BP in southern Africa supplies Rhodesian buyers directly. The London offices did not find out for several years - they gave their [WORDS ILLEGIBLE] "considerable managerial autonomy - and then invented [WORDS ILLEGIBLE] excutives were to [WORDS ILLEGIBLE] or "cosmetic" device.

A French Company [WORDS ILLEGIBLE] would supply the Rhodesian [WORD ILLEGIBLE] and the Shell-BP outfits would sell the same amounts to the French. At least two ministers in Wilson's Cabinet and high-ranking civil servants were told all about it.

"The view of HMG [Her Majesty's Government] at that time . . . as recorded in official documents, was that the legal position of the UK trader companies (Shell and BP) was sound. It was undoubtedly felt to be desirable that the TOTAL arrangement should not be publicly disclosed; this was [perhaps primarily] because of the indication given to the companies that HMG would not disclose it, but also because of the use which could be made of the information by critics of British sincerity."

The report says the government had no hope of stopping the oil. It simply wanted to assert, at the United Nations and elsewhere, that no British oil was flowing to Rhodesia, a literally true and substantively false statement.

A year after the Conservative Party returned to power in 1970, the British comapnies dropped the "cosmetic" swap and went back to direct supplies. Bingham reveals. He concludes, however, that lower-ranking executives in London did not discover this until 1974, and they somehow failed to get their discovery across to the topmost levels.

Bingham incidcates that the whole issue would have remained bruied but for a 1976 report by a U.S. church group, the Center for Social Action of the United Church of Christ. It concentrated on the similar and continuting breaches by the American Mobil Oil and Caltex, a subsidiary of Standard Oil of California and Texaco. But the church team also mentioned the BP-Shell violations.

This produced a letter from Shell's chief, Sir Frank McFadzean, once again assuring the Foreign Office that no British oil was getting to Rhodesia. That assurance, in turn, enabled the new Labor government to repeat its pledge that the sanctions were being honored.

McFadzean, reports Bingham, "cannot be blamed" for the misleading letter, but a subordinate who drafted the document "should not have allowed this impression to be given. Although we fully accept that he had no thought of misleading either his superiors or HMG . . . The need for full disclosure should have need for full disclosure should have been apparent."

Direct shipments from the BP Shell companies to Rhodesian buyers seem to have continued until Owen ordered Bingham into action in the summer of 1977. Then BP and Shell told their South African subsidiaries to stop the supplies.

Lawyer Bingham concludes this way:

"In the event, both HMG and the top management of the Groups, save for limited periods, were ignorant of facts which should have been the subject certainy of consideration and possibly of action. This ignorance led HMG and the top management of the (Groups) unwittingly to make statements and give assurances which they would not have done will fully knowledge of the facts."

Several leading newspapers here have expressed outrage at the disclosures. The Bingham report, with its emphasis on irresponsibility at the highest levels of BP, Shell and the government, is likely to be greeted with skepticism if not derision. But official reports here typically include harsh facts and bland conclusions.

Bingham asked for help from Mobil, Caltex and Compagnie Francaise des Petroles. Total's parent. He says only Mobil gave him documents and they were useless. BP had to cooperate. The British government owns 51 percent of its shares.