Malabo/Madrid - Security forces in Equatorial Guinea have repelled an armed attack on the presidential palace, diplomats said Tuesday.

According to Spanish diplomats in Malabo, a three-hour firefight broke out in the early hours of Tuesday morning.

Reports suggested that at least one soldier and one of the attackers were killed in the fight, although President Teodoro Obiang Nguema was not in the residence at the time.

The attackers apparently arrived in the capital Malabo on small boats fitted with powerful outboard engines and were heavily armed.

The army set up checkpoints in the city on Tuesday and schools were closed.

Guinea, the third-largest oil producer in sub-Saharan Africa, has undergone decades of instability.

British mercenary Simon Mann is currently serving a 34-year jail sentence in the capital Malabo after being found guilty of leading a coup attempt in 2004.

However, the Spanish Ambassador in Malabo, Javier Sangro de Liniers, told national broadcast RNE that the attackers had no political goals and were merely criminals.

Obiang has ruled since seizing control in bloody coup in 1979. (dpa)