ERFURT, East Germany (AP) _ West German politicians are enjoying celebrity status in East Germany's first free election campaign in 40 years.

Chancellor Helmut Kohl, Foreign Minister Hans-Dietrich Genscher and former Chancellor Willy Brandt have been among the visiting campaigners who have drawn crowds of up to 100,000 at election rallies.

Some Communists and members of other leftist groups say the Bonn leaders should stay out of the campaign being waged by their sister parties for the March 18 parliamentary elections.

But most East Germans seem to welcome the support, saying Kohl, Genscher and Brandt are providing their nation with a crucial lesson in democracy.

''The questions being addressed here concern the people in West Germany too,'' said Karl-Heinz Gandre of Erfurt. ''We are one people, and we belong together,'' Gandre said.

Gandre was in a crowd of 60,000 people waving West German flags and chanting ''Germany, united fatherland'' as they greeted Genscher at a rally for the centrist Association of Free Democrats in Erfurt.

Politicians in East Germany's new pro-democracy movements are relatively unknown and inexperienced. They benefit from the reflected fame of the visiting West German politicians, who are well-known from West German television broadcasts that blanketed the country even before the frontiers were opened last fall following a popular movement for democratic reforms.

For the West German leaders, the campaign is an opportunity to shape the future of a new Germany and perhaps establish a power base in this nation of 16 million now that uniting the two countries appears inevitable.

Open politicking is new in East Germany, and some campaign posters have been torn down and defaced. Under the old Communist regime, political signs were virtually sacrosanct.

''Partly, this is still a very undisciplined campaign,'' said Ulli Mueller, another Erfurt resident who came to hear Genscher. ''There's no experience in making democracy work here, because we've been ruled by one man for so many years.''

He referred to former Communist leader Erich Honecker, who was ousted in October after 18 years of hard-line rule.

Communist Premier Hans Modrow remains the most popular politician in East Germany, despite the party's fall from power, according to West German media polls.

Despite his personal prestige, Modrow's party is expected to finish no better than a distant third in the March vote, trailing the Social Democrats and the conservative Alliance for Germany.

Brandt, the architect of the 1970s period of detente between the two German states, kicked off the East German Social Democrats' campaign in Leipzig.

Kohl chose Erfurt to make his debut on East Germany's campaign circuit, addressing a cheering crowd of 100,000. The rally was organized by a three- party coalition, including the East German version of Kohl's Christian Democrats.

Some people in the audience chanted ''Helmut 3/8 Helmut 3/8'' There were also a few hecklers, and fliers reading ''Kohl, do your campaigning at home'' were pasted over campaign posters throughout the city.

''What Mr. Kohl is doing is just party politics,'' said Hannelore Tauer, an East Berlin supermarket clerk. ''It's not doing the West or East German people any good.''

But that seemed to be a minority view.

''The politicians in West Germany ... have done a lot for East Germany before, so I think it's right they come to the election campaign here,'' Gandre said.