JOHANNESBURG, South Africa (AP) _ The government on Monday ordered a West German television correspondent to leave South Africa, the fourth foreign journalist expelled since a state of emergency was declared June 12.

Heinrich Buettgen, 55, correspondent for the ARD television network, was ordered by Home Affairs Minister Stoffel Botha to leave South Africa by midnight Thursday.

Botha said Buettgen had until Thursday morning to appeal the order, and the ARD office said Buettgen would appeal.

The Home Affairs Ministry gave no specific reason for the expulsion, saying only that Buettgen's removal was ''considered to be in the public interest.'' Buettgen has been working in South Africa for four years.

In Bonn, the West German Foreign Ministry said a ranking ministry official, Juergen Sudhoff, had met with South African Ambassador Willem R. Retief to demand Buettgen's expulsion order be withdrawn.

The other journalists expelled from South Africa since June 12 were CBS News cameraman Wim de Vos, Newsweek magazine correspondent Richard Manning, and Israeli journalist Dan Sagir, who reported for the newspaper Haaretz and Israel army radio.

The state of emergency declaration was accompanied by severe new restrictions on reporting by both South African and foreign journalists. The government has warned repeatedly that it was prepared to act sternly against those violating the regulations.