London — LAST week's military raids on Zambia, Zimbabwe, and Botswana have almost certainly destroyed the prospects that a British Commonwealth peace initiative may have had to negotiate a settlement between whites and blacks in South Africa. The attacks have also made it virtually certain that British Prime Minister Margaret Thatcher will come under intense international pressure to join an economic boycott of South Africa.
These were the somber assessments made by London-based diplomats as members of the Eminent Person's Group (EPG) -- the Commonwealth fact-finding team that spearheaded the initiative -- left Cape Town and headed back to their respective Commonwealth capitals last week.
Their return was followed by strong predictions that an emergency meeting of the Commonwealth's 50 members would be held in London in September. Observers here believe that at such a meeting Mrs. Thatcher would be asked to throw her support behind a program of mandatory economic sanctions.
In the House of Commons, Foreign Secretary Sir Geoffrey Howe attacked the raids as ``deplorable acts.'' But he stopped short of endorsing an economic boycott, calling the proposal ``counterproductive.''
The Commonwealth secretary-general, Shridath Ramphal, called the raids a ``declaration of war'' and said the only policy open to the Commonwealth now was economic sanctions.
For Thatcher, the probability of having to face a summit meeting at which angry Commonwealth heads of government would attack her for her reluctance to support a boycott of South Africa is already an embarrassment.
Last November, at a Commonwealth summit meeting in the Bahamas, Thatcher was urged to support a boycott. She managed to avoid doing so by agreeing to the setting up of the seven-member EPG, which was given six months to find a negotiated settlement in South Africa.
If Thatcher continues to reject sanctions, she is unlikely to receive the support of other Commonwealth countries.
In a bitterly worded statement, Sir Shridath, who is the permanent civil service head of the Commonwealth, drew attention to Thatcher's isolation. He went on to say, ``What more do Western countries need to disengage from South Africa and ostracize it from human society in both political and economic terms?
``Those who are supine now must never speak again in righteous terms in the name of justice, morality, and freedom; especially those whose policies support apartheid.''
Ramphal is known to be deeply concerned that the dispute over sanctions against South Africa could rip the Commonwealth apart, leaving Britain -- the founder member -- on the sidelines. Such an outcome would be a grave embarrassment to the Queen, who is head of the Commonwealth.
The EPG will now compile a report on its attempts to open fruitful negotiations with South Africa's leaders. There was talk in diplomatic circles last week that a report would be ready for publication in July. In August, there will probably be a meeting of the EPG with Thatcher along with the leaders of India, Zambia, the Bahamas, Australia, Canada, and Zimbabwe. This meeting would either obtain Thatcher's agreement to an economic boycott or lay the groundwork for an emergency summit gathering of the full Commonwealth in September.
Thatcher's political opponents in Britain are solidly in favor of an economic boycott, and it is certain that the future of South Africa will become a dominant element in inter-party conflict in coming months.
In Westminster it was pointed out that a Commonwealth summit would come only a few weeks before the annual conferences of the main political parties, all of which will have South Africa high on their agendas for discussion.
The Labour Party leader Neil Kinnock, and the leaders of the Liberal-Social Democratic Alliance (SDP) want a ban on trade with South Africa and a halt to all future investment.
The leader of the SDP, David Owen, declared: ``The South Africans have deliberately undermined the Commonwealth peace initiative. They must now be met with sanctions.''