BAMAKO (Reuters) - The leader of the Islamist militant group Ansar Dine has agreed to cease attacks in Mali that have killed dozens of civilians, soldiers and U.N. peacekeepers this year, the president of the West African nation’s top Islamic body said on Monday.

Al Qaeda-linked Ansar Dine and other Islamist groups hijacked a Tuareg rebel uprising in 2012 to seize Mali’s desert north, but they were pushed out by a French-led military operation a year later.

However, they have intensified operations this year, attacking parts of the west and south previously considered secure and raising fears the violence will spill over into other regions.

“I confirm having received from (Ansar Dine leader) Iyad Ag Ghali the cessation of hostilities throughout the country,” Mahmoud Dicko, president of the High Islamic Council, told Reuters, adding that he would soon brief Malian authorities.

In a letter to Dicko, published on Malian news site malijet.com, Ag Ghali said he agreed to stop attacks at Dicko’s request.

“The application of this cease-fire with good faith will allow for the assurance of the security of people and their property (and) promote social cohesion, the key to peace and stability,” Ag Ghali said.

Ag Ghali did not say how long the cease-fire would last or what he expected in return from Malian authorities.

Mali’s government and northern separatist groups signed an agreement last year that aimed to end decades of Tuareg uprisings and allow the army to focus of fighting Islamist militants.

Ag Ghali is a renegade Tuareg commander and has ties to the separatists, but Ansar Dine was excluded from the agreement.

The United States named Ag Ghali a “specially designated global terrorist” in 2013. He has also been sanctioned by the United Nations for his ties to al Qaeda.

Meanwhile, the Islamic State news agency Amaq confirmed on Sunday a pledge of allegiance from a Saharan militant group called Islamic State in the Greater Sahara, which has claimed attacks in Mali and Burkina Faso in recent weeks.

It was the first sign of recognition by leaders of Islamic State for the group, which had declared its allegiance in May 2015 after splitting from an al Qaeda faction.

Analysts say the timing might suggest that the group has proven its worth to the central command. It also shows Islamic State’s growing reliance on foreign affiliates, as the headquarters of its self-declared caliphate comes under attack in Iraq.