Al Qaeda in the Islamic Maghreb (AQIM) claimed responsibility on Wednesday for an attack on two U.N. sites in northern Mali where a peacekeeper from China and three civilians were killed and over a dozen others wounded.

China's Foreign Ministry said four of its peacekeepers were injured and called for an investigation into the attack late on Tuesday on the base in the town of Gao. The country said it has 2,400 peacekeepers stationed in Africa.

Two Malian security guards and an international expert were killed in a later attack carried out with light arms on the U.N. anti-mining operation (UNMAS) in a different neighborhood of Gao, the U.N. peacekeeping mission (MINUSMA) said.

Mali's government and separatists signed a peace accord last year but it has not stopped periodic violence in northern Mali by Islamist militants who have also staged a series of high profile assaults in Burkina Faso, Mali and Ivory Coast.

AQIM said on social media its al-Mourabitoun division fought "crusader occupation forces" in Gao on Wednesday, according to SITE Intelligence Group, a monitoring firm.

MINUSMA confirmed the death toll and said three peacekeepers and 10 civilians had been injured in the rocket or mortar attack. Its head, Mahamat Saleh Annadif, called on the government to ensure those responsible were brought to justice.

The double assault occurred just days after five U.N. peacekeepers were killed and one injured in an ambush on a convoy in central Mali.

In a separate incident on Tuesday, attackers killed three police officers at a station seven kilometers (four miles) from the border of Mali and set the building ablaze, Burkina Faso's Interior Minister Simon Compaore said after a cabinet meeting.

Mali's peacekeeping mission was started in April 2013 after Tuareg separatists and Islamic militants began a rebellion in the desert north.