An international operation was under way on Monday to hunt the killers of two French journalists shot dead in Mali, with a police source in the country's north saying around a dozen suspects had been arrested.

Ghislaine Dupont, 57, and Claude Verlon, 55, were kidnapped and killed by what French Foreign Minister Laurent Fabius said were "terrorist groups" in the flashpoint northeastern town of Kidal on Saturday.

Paris on Sunday blamed terrorist groups for the murder in "cold blood" of two radio journalists in northern Mali, and said French troops would boost security in the restive zone.

Foreign Minister Laurent Fabius said Radio France Internationale (RFI) journalist Ghislaine Dupont and sound technician Claude Verlon were shot dead after being abducted by armed men on Saturday.

The United Nations Security Council has "strongly condemned" the kidnapping and slaying of two French radio journalists in Mali's troubled northeast.

The journalists -- Ghislaine Dupont and Claude Verlon of Radio France International (RFI) -- were found dead after being kidnapped by armed men in the northern city of Kidal.

Two journalists with Radio France Internationale (RFI) were found dead on Saturday after being kidnapped by armed men while working in Mali's far northeast, government and security sources said.

Ghislaine Dupont and Claude Verlon were on their way to interview a spokesman for the Tuareg rebel group the National Movement for the Liberation of Azawad (MNLA) in the rebel stronghold of Kidal when they were abducted outside his home, RFI said.

The Netherlands will send 380 soldiers and four Apache attack helicopters to war-torn Mali following an appeal for more U.N. peacekeepers, Dutch Prime Minister Mark Rutte said on Friday.

The announcement comes after an urgent request by the U.N.'s special representative in the west African country for more blue helmets as its peacekeeping force faces a new surge of Islamist attacks.

The soldier who led a coup that ousted Mali's government and paved the way for a sweeping Islamist offensive has been summoned to appear in court over alleged violence involving men under his command, police and judicial sources said Thursday.

A judicial source said the intention was to question Amadou Sanogo about "the deaths in the last mutiny against him", adding that he would also be questioned "on all violence in recent times" of which his men have been accused.

Islamists fired shells on Wednesday towards airport in Gao, Mali's second-largest city, but did not cause any casualties, a source from the Malian army headquarters said.

"The Islamists fired shells towards the airport in Gao" where French and Malian soldiers are stationed, the source said.

Mali's government has lifted arrest warrants against four leaders of the west African country's ethnic Tuareg rebellion in the name of "national reconciliation", the justice ministry announced Tuesday.

The warrants were issued several months ago against rebel leaders in the National Movement for the Liberation of Azawad (MNLA) and the High Council for the Unity of Azawad (HCUA).

French, U.N. and Malian forces were engaged in a major operation aimed at preventing a resurgence of Islamist rebels in Mali, the French military said Thursday.

"We have engaged, with the Malian army and (U.N. mission) MINUSMA, in a large-scale operation" in the so-called Niger Loop, an area hugging a curve of the Niger River between Timbuktu and Gao, French general staff spokesman Colonel Gilles Jaron said.

Al-Qaida-linked militants said they were behind a suicide car bomb attack in northern Mali that killed two Chadian U.N. peacekeepers and a civilian, in another sign of escalating violence in the west African nation.

"The mujahideen have put to death the Chadian soldiers in the camp who work for France," the leader of a splinter group linked to al-Qaida in the Islamic Maghreb (AQIM), Sultan Ould Bady, told Agence France Presse by telephone on Wednesday.