Angola will release four human rights activists jailed in the wake of a deadly attack on Togo's football team during the Africa Cup of Nations in January, a top justice official said Wednesday.

"They are going to be freed today," Antonio Nito, attorney general for the northern province of Cabinda, told AFP.

Nito said the activists, who were sentenced to three to six years in prison in August, would be freed after the ruling was found unconstitutional under a new law on crimes against state security.

The attack, which killed two members of the Togolese team and injured its goalkeeper, was claimed by the separatist guerilla movement Front for the Liberation of the Enclave of Cabinda (FLEC).

The activists were arrested because they had documents about FLEC and had travelled to Paris for meetings with exiled leaders.

A total of nine people were arrested in connection with the attack, but only two of them had any direct link to the shooting, according to Human Rights Watch.

FLEC separatists have been fighting for Cabinda's independence for more than three decades.

Despite a peace deal in 2006, FLEC factions continue to wage low-level attacks in the oil-rich province that is separated from the rest of Angola by a strip of territory belonging to the Democratic Republic of the Congo.