The self-exile last week of political lawyer Shun Chetty, who rose to prominence as an attorney for the family of slain black consciousness leader Steve Biko, has caused a swirl of controversy here.

It also may pose problems for the main organization financing the defense of blacks in political trials, the South African Council of Churches.

Allegations of tax evasion, unprofessional conduct and financial mismanagement against Chetty, 37, have surfaced since he left South Africa Aug 8. He walked across the border into neighboring Botswana to avoid detection by South African immigration officials. His passport was withdrawn in 1976.

Among the financial disputes surrounding Chetty is one involving $20,000 and the secretary general of the council, Bishop Desmond Tutu. Chetty received thousands of dollars from the council, most of which was collected overseas from organizations and churches to defend young black dissidents who run afoul of this country's strict security laws.

What may prove to be more of a problem for the council is Chett's recent comments in an interview with freelance South African journalist Gavin Robson. Chetty reportedly said that while he was a lawyer here, he actively assisted young blacks leaving South Africa -- an act that is illegal in South Africa.

Because Chetty is identified as the council's principal defense lawyer for political trails, his admission aggravates the council's already shaky position in South Africa, where it faces charges of being a political tool of what are seen here as leftist church groups such as the World Council of Churches. The world council is under constant fire here for its financial aid to guerrilla movements in Africa.

Chetty did not say he encouraged young blacks to join guerrilla groups for military training, which would be a major offense here under the antiterrorism laws. He did not tell Robson how long he assisted youths to leave South Africa, a movement that received tremendous impetus after the 1976 upheavals in black communities, and he did not say how many persons he helped to leave.

Meanwhile, the head of the South African security police, Brig. Gen. Johan Coetzee, told the opposition newspaper, the Rand Daily Mail, that his department had no "specific investigation? into Chetty's political activities. He added, "I can go so far as to say he was not seriously involved politically."

In the interview with Robson in the Botswanan capital of Gaborone, Chetty, who is a South African of Indian descent, said he felt compelled to act.

"In the South African climate it was impossible for me as a black man to retain my impartiality, and every now and then there are things I had to do which would be considered in legal circles as exceeding the bounds of professional duty.

"These things I did knowing full well what I was doing, but the choice I had to face in South Africa was whether I was an oppressed black man or simply a professional doing a job," Chetty said.

"Blacks in South Africa in many cases have no alternative but to flee racist South Africa; the white power mechanization is for the survival of the whites," he added.

Chetty told local papers here he left South Africa because he feared he would be banned, a form of restriction that would have made it impossible for him to continue his work as a political trial lawyer. But many of his associates here found this explanation unsatisfactory.

"Why then didn't he wait until he was banned, if he was going to be?" one associate asked.

Chetty said he had documents that demonstrated how some of his clients were intimidated by the security police for employing him and questioned about their reasons for choosing him.He also told Robson he had papers showing how in six cases, involving about 10 clients, the trials were held and the accused sent to prison before he received any notification from the state of when and where their trials would take place.

Chetty has charged that the government or the security police are at the root of all the allegations against him, which he characterized as attempts to discredit him. Nevertheless, he admits that he has not paid income taxes for the past three years. He told a local paper he avoided the taxes because he was never given a tax number by the internal revenue service.

It also has been revealed that Chetty failed to appear Aug. 9 at a hearing of the Transvaal Law Society, a professional body with disciplinary powers, to answer charges of unprofessional conduct in relation to one political case. Chetty has charged that the real reason for the investigation is to hurt his reputation and to probe the sources of money used for defending clients.

On the subject of the disputed council funds, Chetty said he was "distressed" that Tutu had gone public on a matter the two men had been disputing for 18 months. Chetty said the money was repaid to the council, and Tutu has said he received no accounting for it from Chetty. Tutu said in an interview Friday that he "expects Shun will be able to provide me with the information required."

There also have been allegations in the press that Chetty failed to pay some advocates for their work. Under the South African legal system lawyers act as go betweens for clients and advocates who defend them in court.

Friends and colleagues fear that the Chetty affair will give the government ammunition against other legal professionals who involve themselves in political cases.

"We cannot forget the good work Shun did while he was here, but before he left he should have finished up his business matters better." said one associate.

Chetty and his wife, Fazila, a doctor, plan to go to Britain, where they have been given permission to live.