BRUSSELS/UNITED NATIONS/ GAO, Mali: Al-Qaeda in the Arabian Peninsula has called for jihad in Mali, a monitoring group said Tuesday, after four days of suicide attacks and guerrilla fighting in territory French-led forces reclaimed from Islamist rebels.

The call to holy war from AQAP, the global network’s Yemen-based branch – which U.S. officials have labeled as Al-Qaeda’s most dangerous franchise – came as troops sought to tighten a security lockdown in Gao, the largest city in northern Mali and the target of a string of Islamist attacks.

AQAP condemned France’s month-old military intervention against Islamist groups in the part-desert nation as a “Crusader campaign against Islam,” and called on Muslims everywhere to join the fight against it, the SITE Intelligence agency said.

“Supporting the Muslims in Mali is a duty for every capable Muslim with life and money, everyone according to their ability,” AQAP’s Shariah Committee said in a statement reported by the U.S.-based agency, which monitors extremist Internet forums.

AQAP’s statement said jihad is “more obligatory on the people who are closer” to the fight and that “helping the disbelievers against Muslims in any form is apostasy.”

The statements were an apparent reference to North African countries, notably Algeria, where Islamist gunmen attacked a gas field after the government agreed to let French warplanes use Algerian airspace, unleashing a hostage crisis that left 37 foreigners dead.

France launched its operation in Mali on Jan. 11 after the interim government requested help against Islamist insurgents who had seized the north for 10 months and were advancing into southern territory.

But the Islamists have now started a campaign of suicide attacks, landmine explosions and guerrilla fighting – a troubling turn for France, which is eager to wind down the operation in its former colony and hand over to United Nations peacekeepers.

Troops from Mali and Niger patrolled the streets of Gao Tuesday making periodic arrests, after four days of violence that began with back-to-back suicide bombings and an attack on the city center by fighters from the Movement for Oneness and Jihad in West Africa.

Malian Defense Minister Yamoussa Camara said three Islamists had been killed in the fighting Sunday and 11 captured. Three Malian soldiers were slightly wounded, he added.

Except for the heavy patrols, central Gao was nearly deserted Tuesday.

“People are afraid because of the security situation and because we’re making arrests,” a Malian officer said.

U.N. rights chief Navi Pillay warned the U.N. Security Council that Mali risks being dragged into a “catastrophic spiral of violence” as a result of reprisals.

Pillay said human rights observers are currently in Mali and called on all sides in the conflict to refrain from revenge attacks.

“As the situation evolves, attacks and reprisals risk driving Mali into a catastrophic spiral of violence,” the U.N. human rights commissioner told a Security Council meeting on protecting civilians in conflict Tuesday.

“I call on all parties to the conflict to abide by international human rights and humanitarian law, and to prevent retaliation,” she said.

Paris announced last week it would begin bringing its troops home in March. It wants some 8,000 African troops slowly being deployed to Mali to be incorporated into a U.N. peacekeeping mission.

But U.N. Deputy Secretary-General Jan Eliasson said Monday that “there is still hesitation from the government of Mali.”

In any case, Eliasson added, the situation on the ground would first have to be more stable and any U.N. peacekeeping force there would require a U.N. resolution.

The European Union announced it is set to unblock 250 million euros ($334 million) in development aid to Mali that was frozen after the March 2012 coup which allowed Islamist insurgents to seize cities and territory in the vast arid north of the country.

The aid money will gradually be restored this year, Europe’s development chief Andris Piebalgs told a meeting of EU aid ministers in Dublin Tuesday, adding that the EU was satisfied Mali had taken steps toward restoring democratic government.

Britain also announced a 5 million pound ($7.8 million) aid package to help buy food, medical supplies and clean water for civilians that have been caught up in the conflict.

The aid will also help the International Committee of the Red Cross provide physiotherapy for disabled Malians and psychological care for those affected by the fighting, Britain’s International Development Ministry said.