JOHANNESBURG -- Forty-four theologians from South African universities and seminaries told President Pieter W. Botha Thursday that the country's churches have a clear biblical basis for protesting against apartheid and that Botha's recent attacks on Anglican Archbishop Desmond Tutu and other religious leaders were "un-Christian."

Joining the growing church-state confrontation over the government's clampdown on legal antiapartheid organizations, the theologians said in an open letter published in a Cape Town newspaper that the dispute reflects growing antagonism between the "oppressors and oppressed.

"The basic problem is that the policy of apartheid, however disguised, is racist and unjust and can be implemented only by force and coercion. Such a policy clearly contradicts the Gospel. That is the overwhelming consensus of Christian opinion within virtually all major churches," the theologians said.

Their declaration of support stemmed from Botha's reaction to an attempt by Tutu and other top church leaders to march on Parliament on Feb. 29 to present a written protest against the banning of 17 antiapartheid organizations, including the United Democratic Front, a coalition of 700 protest groups.

Police briefly detained Tutu, the 1984 Nobel peace laureate, along with the Rev. Allan Boesak, president of the World Alliance of Reformed Churches, and the Rev. Frank Chikane, general secretary of the South African Council of Churches.

While the dissident churchmen, representing more than 12 million South African Christians, vowed to fill the vacuum created by the bannings, the white Dutch Reformed Church, with 1.7 million members, has condemned the aborted march on Parliament and has supported the government clampdown.

Botha, in a March 24 letter to Tutu, which the president's office made public, condemned the attempted march and said that no theologian he had consulted could provide biblical support for the church leaders' protest action.

Botha called upon Tutu and other church leaders to "be messengers of the true Christian religion and not of Marxism and atheism."

In their open letter, the theologians argued that the prophets of Israel, including Jesus, often found it necessary to engage in symbolic protest when their appeals for justice were ignored by those in authority.

"In the same way, over the years many church leaders have pleaded, both in private and in public, with those in authority to heed the cries of the victims in our society. This has brought little response and sometimes only rebuke and rejection -- hence the need to put words in action," the theologians said.

Among the institutions they represent are the University of South Africa, the University of Cape Town, the University of the Western Cape, Rhodes University, the University of Natal and St. Joseph's.

The Council of Churches, meanwhile, was seeking legal advice about whether to sue Botha for defamation over his attacks on Tutu and Chikane. It would be the first defamation suit against the president since a change in the constitution in 1983 made such litigation possible.

With the effective banning of the UDF and other anti-apartheid groups, the Council and other church bodies have increasingly viewed themselves as the last legal avenue for nonviolent dissent against the government's policies of racial separation and white minority rule.

After centuries of preaching that apartheid was ordained by God, the white branch of the church modified its policies 18 months ago and said that segregation was no longer required, although it remains acceptable if it does not put any racial group at a disadvantage.

Johan Heyns, leader of the church, has maintained that active protest should be outside the scope of churches, and that civil disobedience should be employed only as a last resort.

Jointly, the black branch of the Reformed Church, with 1.25 million members, and the mix-race Colored branch, with 675,000 members, outnumber whites in the reform movement.