Mikhail S. Gorbachev inspected the site of the Chernobyl nuclear disaster Thursday, and a plant official said the president discussed safety measures taken since the 1986 reactor explosion.

The 57-year-old Kremlin chief visited Chernobyl's nuclear power control room and the hall where turbines generate electricity, said Yuri Risovany, a spokesman for Kombinat, the company running the plant.The April 26, 1986, explosion - the world's worst nuclear power disaster - sent a cloud of radiation around the world and killed at least 31 Soviets. It also shocked many Soviets into reassessing the safety of nuclear power.

Gorbachev met with plant managers and workers and discussed safety measures taken after the explosion, the spokesman said.

Three of the plant's four reactors were operating during Gorbachev's visit, Risovany said. The damaged No. 4 reactor, encased in a steel-and-concrete shell, does not operate.

The visit to the plant, 80 miles north of Kiev, came on the third day of a four-day trip to the Ukraine.

It was the first time the Soviet leader had visited the site of the disaster.

Gorbachev then traveled to Slavutich, a town 30 miles to the west built to house plant workers after the accident. Workers previously lived in Pripyat, a city just a few miles from the striken plant. Gorbachev met with Kombinat officials to discuss their work and returned to Kiev, Risovany said.

In Kiev Monday, Gorbachev met workers, farmers and Communist Party activists and other Ukrainians, the official news agency Tass reported. Gorbachev assured residents concerned about the safety of a nuclear power plant being built on the Crimean Peninsula.

"One shouldn't play around in these matters," Gorbachev told a crowd. "It's serious. Don't think we want to trick anyone. We would only back ourselves into a corner."

The announcement of Gorbachev's visit to Chernobyl was unusual, appearing in the daily Izvestia evening newspaper and not the official Tass news agency. Gorbachev's long talks with workers are generally shown on Soviet television.