MANILA, Philippines (AP) _ The Commission on Elections proclaimed Juan Ponce Enrile a senator today, after the Supreme Court had ordered the opposition leader declared a winner in the May election.

Enrile, a former defense minister, was not present at the ceremony. Later, he told a news conference he probably would take his oath of office Friday, then begin speaking out against what he termed ''anarchy in the administration.''

President Corazon Aquino issued a statement today saying she had ''bowed to the decision of the highest court in the land'' and accepted the decision, despite the defeat of one of her candidates.

Enrile also said he would work vigorously for accountability in government and for an explanation of the security situation in light of recent killings, including the Aug. 2 assassination of Cabinet member Jaime Ferrer, the local governments secretary.

Commission Chairman Ramon Felipe read an official proclamation as about 30 Enrile supporters cheered. The proclamation declared Enrile the winner of the 24th and final position in the Senate, which convened July 27.

Enrile, sacked from the Cabinet last November after an alleged coup plot by his followers, becomes only the second opposition member of the upper chamber. He joins movie star Joseph Estrada, who also ran on the center-right Grand Alliance for Democracy ticket in the May 11 election.

The commission certified that Enrile won 7,964,966 votes, about 73,000 ahead of administration candidate Augusto Sanchez, a former labor minister.

In a ruling Wednesday, the high court ordered the commission to proclaim Enrile and rejected a request by Sanchez for a partial recount. Sanchez claimed he lost thousands of votes because the commission failed to remove the name of a disqualified candidate, Gil Sanchez, from official tally sheets, causing confusion among precinct counters.

The commission had maintained it could not proclaim Enrile because several thousand votes remained untallied nearly three months after the balloting. The commission had approved Sanchez's request for a partial recount and maintained this could also affect Enrile's standing.

Enrile's supporters claimed the commission's refusal was part of an administration plot to deny the former defense minister a place in the Senate.

The Harvard-trained lawyer served as defense minister under deposed President Ferdinand Marcos for nearly 17 years but then helped lead the February 1986 revolt which led to his ouster. Enrile served in President Corazon Aquino's Cabinet until she fired him Nov. 23.

Mrs. Aquino today named Ferrer's brother as his successor and asked the Senate to confirm the appointment.

Mrs. Aquino gave no reason why she chose Juanito Ferrer, 65, for the post. Juanito Ferrer received a civil engineering degree from the University of Oklahoma in 1957 after a career as a guerrilla leader during World War II and as an army battalion commander during the campaign against Communist Huk insurgents in the early 1950s.

The speaker of the House of Representatives, meanwhile, called the police and military incompetent and said Defense Secretary Rafael Ileto should take responsibility for Ferrer's murder and many other unsolved crimes.

Speaker Ramon Mitra issued the rebuke while voicing alarm over the inability of the police and military to prevent or solve a nationwide wave of killings that has claimed the lives of some 600 policemen and soldiers.

''Some of these killings have been so glaring, it scares our people,'' Mitra told foreign correspondents. ''One wonders, if these people can't protect themselves, how can they protect other people? Somebody has to stand up and take reponsibility.''

''Secretary Ileto cannot escape responsibility for this,'' Mitra said.

Communist rebels have claimed responsibility for about half the killings and have vowed more attacks.

Killings have continued despite Mrs. Aquino's pledge to crush leftist and rightist extremists within five years. Last Sunday she announced ''sweeping new measures'' to curb crime, which has jumped by 30 percent in Manila this year.