The impoverished West African nation Benin said its troops defeated an airborne attack by "foreign mercenaries" here yesterday.

A government communique did not identify the mercenaries, except to say that they were "in the pay of international imperialism."

Benin's President Mathieu Kerekou said in a broadcast that the attackers flew in Saturday night, and fighting began at dawn.

Kerekou came to power in 1972 in a coup and proclaimed the country a socialist state in 1974.

Radio appeals were broadcast every five minutes in French, the official language, and Fon, the local language of the Cotonou region, calling for blocking all roads out of the capital.

Military authorities commandered taxis and loudspeaker-equipped cars normally used to advertise the national lottery. They warned foreigners to stay off the streets.

Local "revolutionary defense committees" were instructed to arrest any suspicious-looking foreigners.

Because of personal and regional animosites, the former French colony, known as Dahomey until 1975, has been politically unstable since gaining independence in 1960. It has gone through at least eight military coups or attempted coups since then.

Considered one of Africa's poorest nations, Benin has an area of 43,000 square miles and a population of about 3 million. The economy is essentially agricultural, and Benin depends heavily on French aid.