BRUSSELS, JUNE 22 -- President Mobutu Sese Seko of Zaire announced diplomatic and commercial reprisals against Belgium today over what he called interference in his nation's internal affairs by its former colonial ruler.

The Belgian government froze loans to Zaire May 25 after news reports that Zairian government troops had massacred scores of students at a university in the southern city of Lubumbashi. Belgium has pressed for an international inquiry into the incident.

Mobutu, speaking after a special cabinet meeting in the east Zairian lakeside town of Goma, accused Belgium of repeated interference in his country's affairs and of adopting an "unfriendly attitude."

Mobutu announced that beginning July 1 Belgium must close all but one of its seven consulates in Zaire and that the Belgian national airline, Sabena, would be limited to two flights to Kinshasa a week, not four, according to a report by the Zairian news agency AZAP.

Mobutu said Zaire also was renouncing an agreement under which Brussels was to forgive some of its debt and would send home development aid workers paid by Belgium.

In Brussels, the government denied that it was interfering in Zaire's internal affairs, saying it had simply asked for clarification of the "serious incidents" at Lubumbashi.

A commission of inquiry set up by the Zairian parliament has accused local officials of orchestrating the murder of at least 12 students on the night of May 11-12. Four officials were arrested Thursday night in Lubumbashi, AZAP said today.

Some Zairian opposition groups have charged that Mobutu's personal guard carried out the killings, which followed anti-Mobutu demonstrations on campus, and have put the death toll at up to 150.