HEGYESHALOM, Hungary--Thousands of East Germans, crying, laughing and shouting with happiness, poured into Austria from Hungary early yesterday en route to freedom in West Germany.

They began driving across the border at midnight as Hungary removed the frontier barriers to allow more than 7000 East German refugees to escape to the West.

It is the largest mass emigration of East Germans to West Germany since the Berlin Wall was built in 1961 to stem the flow across the border.

Hungary, in a decision announced Saturday, was the first Eastern bloc government to help the citizens of another communist country to freely leave their homeland.

East Germany promptly attacked the Hungarian decision, saying Budapest had "directly interfered" in East Germany's internal affairs.

"The Hungarian government has chosen to illegally allow East German citizens to travel to West Germany in violation of international treaty," the state news agency ADN said.

The agency said Hungary, "under the guise of humanitarianism, has engaged in the organized smuggling of human beings."

At this frontier town 120 miles northwest of the Hungarian capital, border guards gave only cursory checks to East Germans.

As the first groups crossed, hundreds of others waited in their cars, forming growing lines at the main border crossings.

Eight of 18 lanes at the Hegyeshalom crossing were open as the jubilant East Germans drove through. They honked their horns, cheered and whistled, releasing emotions pent up by days and weeks of waiting for a decision by Hungarian authorities. Some refugees waved bottles of foaming champagne from the car windows.

Once on the Austrian side of the massive border barrier, many East Germans jumped from their cars and danced with joy.

A statement yesterday by the official Hungarian news agency MTI said, "Hungary has decided to make it possible for the East German citizens staying in Hungary and refusing to return home to leave to any country which is prepared to let them through or receive them."

Interior Minister Istvan Horvath instructed the police and border guards to let East German citizens leave Hungary with their East German travel documents at any border point.

The Hungarian foreign minister, Gyula Horn, suggested on Hungarian television that tens of thousands of other East Germans now vacationing in Hungary also may choose to leave for the West along with those in the refugee camps.

To make the exodus possible, he said, Hungary decided to suspend a 1969 agreement with East Germany, a Warsaw Pact ally, saying Hungary should not take into account West Germany's claim to East Germans.

The fate of the refugees had been discussed for weeks by East and West Germany, with Hungary insisting it was primarily a bystander interested in seeing a solution. The communique said, "The talks between East Germany and West Germany ended in failure." It did not elaborate.

"There are about 60,000 East Germans now in Hungary," Horn said in the television interview, referring to thousands who have not registered with the West German Embassy in Budapest to leave and are formally in Hungary as vacationers.

West Germany, which offers East Germans automatic citizenship and help getting settled, has set up refugee camps in Bavaria.

"This is a humanitarian decision and an act of European solidarity. I am deeply thankful to the Hungarian government," Chancellor Helmut Kohl of West Germany said in Bonn.