A bomb exploded in the top floor of the controversial Center for International Affairs early this morning, tearing apart the walls and ceiling of the Center's third floor library and reading room and damaging books and papers.

No one was injured in the blast, which went off at 1:02 a. m., although two Harvard policemen and a Cambridge fire marshal were entering the front door of the building just as it exploded.

Harvard police received an anonymous call at 12:38 a. m. warning of the blast and cautioning, "This is not a joke. Remember the Brooklyn courthouse and California. Get the janitor out of the building. This is not a joke."

The building was unoccupied at the time of the blast. Two students were studying in the biology labs next door but left the building before the bomb exploded.

The bomb apparently did not damage rooms on far side of the Center's third floor or the first two floors, ac-according to Archibald Cox, Williston Professor of Law and Harvard's crisis trouble-shooter. There was no estimate on the damages.

The explosion followed by one year and three weeks a violent Weatherman raid on the Center-one of the first violent actions in the country by the radical group-in which several employees were beaten. Eric Mann, now in prison in Billerica, was one of the people convicted of the raid.

Through last year, the CFIA was the target of a full-fledged campaign by Harvard-based radical groups critical of its role in American foreign policy. On April 9 about 200 members of the November Action Committee disrupted a meeting of the CFIA's visiting committee and one student was severed from the University.

Anticipating possible trouble, many of the personal files of professors with offices in the Center had been removed earlier this year and extra security precautions had been taken.

Cox said the phone tip, which also went to the Boston Globe and Cambridge police, came from a girl who "sounded very nervous." She called the building the Center for International Studies, and said the bomb would go off in six minutes.

On receiving the call, the Harvard police sent one officer to the Center to warn any persons inside. After clearing the building, the officer and a Cambridge fire marshal waited outside for 20 minutes before re-entering. The bomb exploded as they started in to check the premises.

Robert Bowie, director of the CFIA, who arrived at the Center just after the bomb went off, would not comment on who did it. He added that the bomb was "either in the third floor reading room or the men's room and it would be perfectly easy for anyone to put a bomb there."

"The Center does a variety of research on defense policy," Cox told reporters at 2:15 a. m., adding that none of the research is classified.

Fifteen per cent of the Center's budget comes from government funding. The bulk of the remaining 85 per cent is contributed by private foundations like the Ford and Rockefeller Foundations, according to the Center's 11th annual report in 1969.

Of the government funds, five per cent is from the Agency for International Development; 4.9 per cent from the National Science Foundation and National Institute of Health; and 4.2 per cent from the Department of Defense, the report stated.

A non-credit seminar on non-violence was scheduled to meet in the Center last night, Benjamin H. Brown, advisor to the Fellows in the CFIA, said last night. He did not know if it had changed locations.