European Community leaders Friday approved a $1 billion emergency aid package for the Soviet Union designed to fight food shortages and bolster President Mikhail S. Gorbachev.

The proportion of grants and loans still had to be decided, however, and Britain, France and Germany cautioned against overloading the troubled Soviet economy with debt.Approval of the emergency aid came at the start of a two-day EC summit.

"All, without exception, are in agreement to give immediate help to the Soviet Union," summit spokesman Pio Mastrobuoni said.

The European leaders said the Soviet food problem had more to do with poor distribution than with shortages. Italian officials said the EC food would be targeted for Moscow and Leningrad.

The EC leaders also were worried about saving Gorbachev, whose political hold is under constant challenge from opponents, including hard-liners and various quarters of Soviet society.

German Chancellor Helmut Kohl denounced attempts to undermine Gorbachev and warned it would be a lot more costly to the rest of the world should Gorbachev fall than to offer emergency aid now.

The Soviet government said on Thursday it had already received 1,700 tons of food and 800 tons of medicine and other aid for the difficult winter ahead.

Earlier Friday, Prime Minister John Major of Britain urged the European Community not to rush into a single currency in its drive for European unity.

"I don't think anybody in the community wants confrontation," said Major, who replaced Margaret Thatcher last month after her combative stance in Europe helped topple the longtime British leader.

But he added, "We can't just leap at it (a single currency). . . . We need to see if it works. We need to see if people want it."