(Adds military declares three days mourning, paragraph 7)
By Vincent Fertey
NOUAKCHOTT, Sept 20 (Reuters) - Mauritania said on Saturday that 12 of its soldiers abducted in an attack claimed by al Qaeda were found with their heads cut off, and it appealed for international support to fight terrorism.
The soldiers had been missing since Monday, when gunmen ambushed their patrol in the northern Zouerate iron ore mining region of the West Saharan Islamic state, which became a modest oil producer in 2006.
Al Qaeda's North Africa wing had claimed responsibility for the ambush and said it was holding the soldiers.
The attack, the second deadly strike by al Qaeda against the Mauritanian army in less than a year, posed the first major security challenge to the senior officers who last month toppled President Sidi Mohamed Ould Cheikh Abdallahi in an Aug. 6 coup.
Colonel Ahmed Bemba Ould Baya, secretary general of the High State Council which took power after the coup, told Reuters the kidnapped soldiers' corpses were found on Saturday in the Tourine area, 70 km (45 miles) from Zouerate.
"Their bodies were found this morning after a search ... they were mutilated and had their heads cut off," he said, adding that the victims' families had been informed.
The dead soldiers would be buried with military honours and Mauritania's military rulers declared three days of mourning.
Baya said the attack and its deadly outcome showed that Mauritania needed international support to fight terrorism.
"This tragic episode puts the international community face to face with its responsibilities," he said.
"We need its help," he added. The army was reinforcing security on the frontiers and in strategic economic zones.
The United States and the European Union, which had backed Abdallahi as an ally in the U.S.-led global war on terror, have strongly condemned the coup and suspended some non-humanitarian aid, which had included U.S. training for Mauritanian troops.
But Baya said Mauritania's new military rulers were an even more likely target for al Qaeda "because we're perceived as close to the West".
"HOLY WAR" CALL
Following the Aug. 6 coup, the al Qaeda Organisation in the Islamic Maghreb called for a "holy war" in Mauritania.
It said the generals and colonels who toppled Abdallahi in the coup were probably acting with a green light from "infidel states; America, France and Israel".
The coup leader, General Mohamed Ould Abdel Aziz, vowed after his takeover that he would crack down on militants.
Al Qaeda had claimed an earlier attack in December against the Mauritanian army in which four soldiers were killed. In 2005, gunmen from the same group then calling itself the Salafist Group for Preaching and Combat (GSPC) killed 15 Mauritanian soldiers in a raid on a northeast garrison.
Late on Friday, Mauritania's military-backed government had also appealed for international "solidarity" to confront a terrorism threat it said had targeted other countries in the region such as Mali, Algeria, Chad and Niger.
"I seize this opportunity to ask the international community to take seriously this very grave threat to the stability of the region," Communication Minister Mohamed Ould Mohamed Abderrahmane Ould Moine told a news conference.
The United Nations, the African Union and the EU have all called on Mauritania's ruling junta to release deposed President Abdallahi, the country's first freely-elected leader who won a 2007 presidential election.
Asked about this, Moine said some governments were "disinformed about what is happening in Mauritania".
"We want to revise our democratic process and we accuse the former president, with pretty conclusive proof, of having sought to block the democratic process and limit freedoms, and of corruption," he told Reuters after the news conference.
The coup leader, former presidential guard chief Abdel Aziz, overthrew Abdallahi after he had ordered the dismissal of him and other military chiefs. (Additional reporting by Manon Riviere and Hachem Sidi Salem; Writing by Pascal Fletcher; Editing by Dominic Evans)