By David B. Ottaway Washington Post Staff Writer

Forty-eight House members have written Zairian President Mobutu Sese Seko telling him they are "disturbed" by reports of corruption and human rights abuses in his country, including a recent bloody government crackdown on opposition elements and the arrest of one of its leaders.

The Feb. 5 letter said reforms were "urgently needed" and warned that "it is difficult for members of the United States Congress to continue sending U.S. military and economic aid in light of current political conditions."

The letter was triggered by a demonstration in the Zairian capital of Kinshasa Jan. 17 that Zairian police broke up by arresting hundreds of participants, including opposition leader Tshisekidi wa Mulumba. Some reports said the police opened fire, killing three and wounding scores of others, but the government has denied there were any deaths.

Tshisekidi, who met many U.S. congressmen during a December visit here, is a leader of the Union for Democracy and Social Progress and had just returned home when he attempted to address an opposition rally.

The issue of human rights abuses in Zaire has surfaced in Congress from time to time over the past decade, but seldom have so many legislators written such a strong warning about the possibility of a cutoff of U.S. aid, which is scheduled to be $46 million this fiscal year.