January 1, 1983

After a marathon 20-hour session, Governor Kean and the New Jersey Legislature enacted a package of tax measures early today that eliminates the need for $150 million in budget cuts the Governor had scheduled to begin Saturday. The package includes a Republican-sponsored 1-cent increase in the state sales tax, to 6 percent, that will take effect Monday, and a Democratic-sponsored increase of 1 percentage point in the state income tax, to 3.5 percent, on annual incomes above $50,000. The income-tax increase will affect earnings in 1983. Governor Kean signed the bills in his office shortly before 8 A.M. after a night of frequent meetings with legislative leaders and his staff. Package Called a Compromise Mr. Kean said he had mixed feelings about the measures - a reluctance to impose increased taxes but a sense of relief that further budget cuts had been avoided.

In his first year in office, Secretary General Javier Perez de Cuellar says, his greatest achievement was his remarkably blunt account of the United Nations' impotence. ''It is this report that contains something necessary,'' he said in an interview. ''My contribution is that I had the courage to sign the report.'' The document, issued in September, was largely a record of failure with some modest proposals for curing the world body's paralysis. It described the many arenas where the United Nations was unable to avert war or bring peace, deplored the repeated defiance of the Security Council, urged the Council to move in on conflicts before they erupted and promised that Mr. Perez de Cuellar would also practice preventive diplomacy to head off potential disputes.

At least four powerful bombs exploded in lower Manhattan and downtown Brooklyn within 90 minutes last night and injured three police officers, the police said. The bombs went off at Police Headquarters and three Federal buildings. One police officer was critically injured by the explosion at headquarters and the other two were injured by the explosion at the Federal jail in lower Manhattan, according to Sgt. Ed Burns, a police spokesman. In addition, the sergeant said, a number of ''suspicious packages'' were found next to other city and Federal buildings - including City Hall - and were being checked by explosives experts.

A strike threatened against the Hudson, Harlem and New Haven commuter rail lines was averted last night when the five unions still without new contracts agreed to work and continue negotiations. Richard Ravitch, chairman of the Metropolitan Transportation Authority, announced shortly after 6 P.M. that there would be no interruption in service on the rail lines, which carry 180,000 riders a day. Mr. Ravitch said one of the unions, the United Transportation Union, which represents conductors, brakemen and ticket takers. had agreed to a one-month extension of the talks. The four other unions, he said, had agreed to keep talking. He said he was hopeful agreements would be reached with the five unions during the next month.

The Soviet Union issued a statement through Tass, the official press agency, today declaring that its troops will remain in Afghanistan until longstanding Soviet conditions for their withdrawal are met. The statement appeared to be intended to reassure the Soviet-backed Government of Afghanistan and to curb speculation in the West that the new Soviet leader, Yuri V. Andropov, might be preparing to accept a face-saving settlement to extract more than 100,000 Soviet troops from a seemingly intractable war. The statement, while not quite as authoritative as an official Government pronouncement, is regarded as a clear indication of Moscow's views. It reaffirmed the terms set out by the Afghan Government in May 1980 and August 1981, which have formed the Soviet position on the war. These are that Soviet troops will be withdrawn once ''foreign armed intervention,'' meaning Moslem guerrillas fighting with Western backing, is ended. In addition, the Afghan leaders have demanded ''dependable international guarantees'' against a resumption of the fighting.