Security forces in Azerbaijan have killed four alleged extremists the government suspects were plotting terror attacks, the Caspian Sea country’s State Security Service says.

The service said the suspects were killed in a shoot-out on January 31 during a search operation that was launched after they opened fire at security forces.

A fifth alleged member of the group was taken into custody.

According to the security service, the suspects were connected to an unspecified religious extremist group abroad and planed a series of terrorist attacks on Azerbaijan's territory.

It did not say where the shoot-out took place.

It was impossible to verify the statement by the authorities in the tightly controlled former Soviet republic.

Based on reporting by trend.az and Interfax