OSLO, Norway (AP) _ Czechoslovak President Vaclav Havel warned Tuesday it will take vigilance and care to keep the ethnic minorities of Central Europe from turning on each other as ''proxies for the totalitarian system.''

Some groups are seeking a focus for their anger after discovering the extent of ''the awful legacy left us'' by decades of Communist rule, Havel said during a debate about ethnic conflicts at a conference in Norway's capital.

The four-day seminar, which began Sunday, was called by 1986 Nobel Peace Prize winner Elie Wiesel to explore the roots of ethnic, religious and political hatred and how to overcome it. About 70 world leaders, Nobel laureates and activists were attending the gathering.

Lithuanian President Vytautas Landsbergis, who wants to lead his Baltic republic out of the Soviet Union, agreed that long-suppressed ethnic conflicts have boiled to the surface in countries where democracy is taking hold.

''Maybe this is why Western Europe, even now ... strangely interprets Eastern Europe's spring as a winter of frightening instability,'' Landsbergis said.

French President Francois Mitterrand said in order to maintain peace, the world must cooperate to enforce international law. He had a timely example to offer - the Persian Gulf crisis.

''This is an appeal for courage,'' Mitterrand said, reminding listeners of Nazi expansionism in World War II. ''We must refuse from the outset (Iraq's) use of force.''

He said France is fully committed - with air, sea and land forces - to countering Iraq's Aug. 2 invasion of neighboring Kuwait and threats to foreigners trapped in the two countries.

''International law must prevail over force, over antagonism,'' he said.

He pointed out that Western Europe, despite two conflagrations this century, had found peace through economic cooperation.

''We could call it a victory over hate,'' Mitterrand said.

Mitterrand urged the eventual inclusion in the European Community of East Bloc nations that have abandoned authoritarian Communist systems.

Havel said he was optimistic that the ethnic groups of Eastern Europe could eventually live in peace.

''If I speak of the nationalist hatred in Central and Eastern Europe, I am not talking about it as our certain future but as a potential threat,'' he said.

After four decades spent in the Communist mold, ethnic groups are rediscovering their individuality, he said.

''After all they have gone through, they feel a natural need to make their existence quickly visible,'' he said.

Havel said it will take care to keep the ethnic groups from turning on each other as ''proxies for the totalitarian system.''