* Paris under pressure to ensure security in northern Mali
* Some 150 troops moved to Tuareg rebel stronghold Kidal
* French and Malian troops hunt journalists' killers
* Le Monde says hostage takers include AQIM member
France will stick to its timetable for withdrawing troops from Mali despite a resurgence in violence and the killing of two French journalists, Foreign Minister Laurent Fabius said on Tuesday.
France, which sent soldiers to its former colony in January to combat militants who had taken over large swathes of Mali, has already delayed by two months plans to reduce troop numbers from 3,200 to 1,000 by the end of the year.
Speaking on Radio France Internationale, Fabius said France had moved 150 soldiers from the south to Kidal, the northerly Tuareg rebel stronghold where instability has grown in recent months, and where the journalists were abducted.
"President (Hollande) immediately decided to strengthen our presence in Kidal, but that does not call into question the calendar and the reduction of French forces," Fabius said.
Malian troops and a U.N. peacekeeping force will also be reinforced, he said.
France launched air strikes and sent troops into Mali in January to drive back advancing al Qaeda-linked rebels, fearing they could make Mali a base for attacks in other countries.
The Islamists scattered and a new president, Ibrahim Boubacar Keita, was elected in August.
ELECTION THIS MONTH
Legislative elections are due on Nov. 24, and Malian and international forces have launched a big operation against Islamist groups in the desert of northern Mali to prevent a recent upsurge in attacks threatening the conduct of the vote.
Kidal itself has been thinly policed, however. About 200 U.N. peacekeepers (MINUSMA) are officially in control of security, with Malian forces largely confined to base, and most of the 200-strong French contingent focusing on the Adrar des Ifoghas mountains, for years a hideout for militants.
On Tuesday, seven French investigators arrived in Mali to support the hunt for the killers of the RFI radio journalists, Claude Verlon and Ghislaine Dupont, a police source said.
The French daily Le Monde reported on its website that three of the four abductors had been identified by French intelligence and military as Islamists from a Tuareg clan, after a document was found in a car abandoned at the scene.
One of them was a member of al Qaeda's north African arm, AQIM, and was linked to the kidnapping of two French hostages in 2011, Le Monde said, citing a local and a French government source. It said all three had at some time been questioned by French forces.
The French foreign and defence ministries declined to comment, while the DGSE external intelligence service could not immediately be reached.
"What I can tell you is that the investigation is moving forward, but I can't tell you who has been arrested or how many people," Kidal governor Adama Kamissoko told Reuters.