ROME, DEC. 14 -- Leaders of the 12 European Community countries, alarmed by the growing political threat to President Mikhail Gorbachev, decided today to send $1 billion in fresh emergency aid to the Soviet Union to help alleviate consumer discontent over food shortages.

The 12 heads of government also agreed to stand firm with the United States in warning Iraqi President Saddam Hussein to withdraw from Kuwait by Jan. 15 or face a possible Western military assault to evict his forces from the occupied sheikdom. The leaders are here for a two-day meeting to launch ambitious efforts to accelerate the drive toward political and economic union in this decade.

Despite a plea in an open letter from President Bush to avoid linking Kuwait "with other issues," the European leaders were expected to issue a declaration when their meeting concludes Saturday reaffirming their desire to move quickly toward an international peace conference on the Middle East soon after the Persian Gulf crisis is resolved. British Foreign Minister Douglas Hurd said the EC declaration would suggest "no linkage but sequence."

Italy's Foreign Minister Gianni De Michelis said that on behalf of the community, he still planned to see his Iraqi counterpart, Tariq Aziz, in Rome when Aziz returns from Washington, despite continuing problems between the United States and Iraq in fixing dates for the Aziz visit and a reciprocal trip to Baghdad by Secretary of State James A. Baker III.

De Michelis stressed that "we shall act in parallel" with the Bush administration, but if the U.S.-Iraqi dialogue is aborted because of disagreement over dates for the Aziz and Baker trips, the Europeans would reconsider their options.

"Dates are a matter of tactics rather than strategy," he said. "If there is a genuine change in the situation, we will review any discussions in that light."

The gulf crisis was discussed at length over dinner after the 12 government leaders spent much of their first day assessing the plight facing the Soviet Union and its former allies in Eastern Europe. In offering a new infusion of emergency aid, the EC leaders said they would extend much of the assistance, especially food, as a gift in an attempt to minimize any additional debt load for the beleaguered Soviet economy.

Fearing that a tardy rescue effort could trigger economic chaos and a stampede of desperate immigrants toward their affluent countries, the West European leaders also agreed to send nearly $2 billion in assistance to East European states to help their fragile economies adjust to free markets and survive the coming winter.

Much of the new aid to Eastern Europe will be used to tighten Western links with Hungary and Czechoslovakia by hastening the convertibility of their currencies. In countries where more desperate conditions prevail, such as Bulgaria and Romania, nearly $300 million in urgent food and oil supplies will be delivered soon.

German Chancellor Helmut Kohl, whose country has agreed to funnel more than $6 billion in bilateral aid to the Soviet Union, appealed to his European peers to expedite all assistance, especially food and medicine, to thwart a potential political challenge that could topple Gorbachev and terminate his reforms.

Kohl's plea was backed by French President Francois Mitterrand, who was quoted by his spokesman as saying, "We can't wait any longer or we may regret any failure to move more quickly" to help the Soviet leader surmount his domestic critics.

The new British prime minister, John Major, making his diplomatic debut on the European leadership stage, concurred with the need to speed up aid to the Soviets but expressed some caution about the risk of squandering supplies and overburdening the dilapidated Soviet transport network.

Major warned that an avalanche of food aid for the Soviet Union could crush whatever nascent market system is evolving there and would only worsen the country's economic prospects in the long run, according to British government sources.

But the British leader strongly endorsed the idea of a European energy charter, conceived by Dutch Prime Minister Ruud F.M. Lubbers, aimed at helping the Soviets harness their vast oil and natural gas reserves to provide a strong foundation for economic growth.

In contrast to what Europeans viewed as the stubborn manner of his predecessor, Margaret Thatcher, Major radiated a new kind of cooperative spirit that was welcomed by the other leaders, various delegation sources said. While he voiced lingering British skepticism about any further surrender of national sovereignty to European institutions, Major impressed his peers by going out of his way to proclaim that Britain sought to play an active role in shaping the form of a more integrated Europe.

British government sources said Major will be more inclined than Thatcher to pursue compromise and work with other leaders who share his views. Today, for example, he teamed with Lubbers to challenge an initiative presented by Kohl and Mitterrand for the community's leaders to undertake new measures to integrate their foreign and security policies.

The Dutch leader, in a letter expressing "serious doubts" about the French-German initiative, warned that the community would become less democratic if such enormous power were concentrated in the hands of the 12 government leaders to the detriment of other institutions. He said the voices of the EC's 340 million citizens could be heard more effectively if greater powers were given to the European Parliament.

Britain, under Major, has continued to emphasize that Western Europe must not move so fast toward common defense policies that the future existence of the North Atlantic Treaty Organization is called into question. More than any of the 12 EC members, Britain wants to preserve NATO to sustain a U.S. defense role in Europe, despite the vanishing Soviet military threat.