Manila  - Unidentified gunmen shot dead a leftist activist as he opened the door of his home in the southern Philippines, a human rights group said Tuesday.

The victim, Rolando Antolihao, was a coordinator for the left-wing Bayan Muna (People First) party in Davao del Norte province, some 990 kilometres south of Manila.

He was the third Bayan Muna official to be killed this year, according to Kelly Delgado, a regional official of the rights group Karapatan.

Delgado said Antolihao suffered seven gunshot wounds to his body.

"The assassins knocked on the victim's house, and when he opened the door, he was shot several times," he said.

Antolihao's killing came just four days after a Bayan Muna coordinator in nearby Compostela Valley province was killed by gunmen aboard a motorcycle.

According to Karapatan, 43 people have been killed in 38 cases of extrajudicial executions in the Philippines from January to September 2008.

Most of the victims were affiliated with leftist, labour and people's rights organizations.

The murders of activists in the Philippines became controversial in 2006, when the number of victims of extrajudicial killings rose to 210, based on a tally of Karapatan.

Leftist and human rights groups have accused government security forces of being behind most of the killings, as well as disappearances of activists.

The military has denied the allegations despite a fact-finding mission that showed that its anti-insurgency campaign was fuelling deadly attacks on activists. (dpa)