On the first day of a historic summit disrupted by student protests, Mikhail S. Gorbachev said Monday that the Soviet Union must share the blame for a cold war that divided the two countries for three decades.

"Very probably we are also responsible for that period to a certain extent," the Soviet leader told China's President Yang Shangkun.China's leaders moved the welcoming ceremony to the airport from a central Beijing square to avoid a confrontation with tens of thousands of rebellious students camped out on the plaza for a third day.

In remarks broadcast on Chinese television, Gorbachev expressed "sorrow and regret" for the bad blood of the past and said "this period has come to an end."

Gorbachev, 58, arrived Monday for the first Sino-Soviet summit since Nikita Khrushchev met Mao Tse-tung in 1959 in acrimonious talks that contributed to rapidly deteriorating relations.

The two nations nearly went to war after border fighting broke out in 1969 and have since been at odds over the Soviet intervention in Afghanistan.

Both sides agree that Gorbachev's meeting Tuesday with 84-year-old senior leader Deng Xiaoping will normalize government and party ties and help spur economic, cultural and academic contacts.

"The way toward this meeting was not an easy one," Gorbachev said at a later banquet speech. "It required from both sides wisdom, responsibility and perseverance in removing the negative aggravations and prejudices that marred our relations for so many years."

Gorbachev also stressed that "the improvement of Soviet-Chinese relations is not directed against any third country. In the final analysis, the entire world community stands to gain from that improvement."

But the summit got off to a rocky start as up to 150,000 people, half of them students, occupied Tiananmen Square - China's symbolic seat of power - in a massive protest for a more open and democratic society.

Soviet Foreign Ministry spokesman Gennady Gerasimov, in a briefing, said the demonstrations would disrupt plans for Gorbachev to lay a wreath on a monument to revolutionary heroes in the center of the square Tuesday.

"Physically it's impossible. The place is taken up by demonstrators," he said.

Gerasimov said the Soviet side understood China's difficulties in coping with the students. "We have similar experiences and have lived through some difficult times," he said.

The demonstrators, including about 2,000 students in the third day of a hunger strike, defied police orders to vacate the square, forcing authorities to cancel a planned welcoming ceremony outside the Great Hall of the People next to the square.

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(Additional information)

Will Soviet get a hug?

Will they or won't they?

The big question when the tightly orchestrated Soviet-Chinese summit between Mikhail S. Gorbachev and Deng Xiaoping begins Tuesday is whether the leaders will embrace to end 30 years of strained relations.

Deng, the 84-year-old paramount leader of China, hugs some foreign dignitaries and shakes hands with others. His choice of welcome is seen as a sign of his personal feeling toward the guest or his nation.

When Soviet Foreign Minister Eduard Shevardnadze visited Deng in Shanghai last February he received a warm and lengthy handshake, but no hug. Schevardnadze referred to the Chinese leader as "comrade," but the socialist honorific was not returned.