MANILA, March 19 (Xinhua) -- There are at least 10 foreign terrorists lurking in the southern Philippines, Philippine Defense Secretary Delfin Lorenzana said on Tuesday.

Lorenzana said that his assessment is that many terrorists who went to the Middles East to join the Islamic State (IS) militants have gone back to their respective countries.

Analysts say that many IS cadres have decided to leave the Middle East after losing its major strongholds in Syria and Iraq. The militants have reportedly targeted the Philippines as in their plan to build an IS caliphate in Southeast Asia.

"While (IS militants) are losing their territories there (in Iraq and Syria), they are fleeing, they are going back to their own countries. Now, if we have Filipinos fighting there in Syria, then we might expect them to be coming back here," Lorenzana said.

Nevertheless, he said that the Philippines is "intensifying its (security) cooperation" with Malaysia and Indonesia to prevent the militants from crossing borders.

Lorenzana further said that Philippine security forces have intensified their operation to eliminate the IS-linked militants in the southern Philippines. "I do not believe that they are growing in number here," he added.

However, a senior military official, speaking on condition of anonymity, said there are about 40 to 100 foreign terrorists currently embedded with various local terrorist groups in the Philippines.

Last week, Maj. Gen. Cirilito Sobejana, commander of the Philippine Army's 6th Infantry Division based in Mindanao, claimed that the military troops killed a foreign terrorist in Shariff Saydona Mustapha town in Maguindanao after troops shelled a camp of Bangsamoro Islamic Freedom Fighters (BIFF).

Security officials have earlier said that there are 40 foreign militants in the country. The foreign terrorists, who include Indonesians, Malaysians, Pakistanis, Moroccans, Egyptians, and Singaporeans, are mostly in Sulu archipelago and Maguindanao province in central Mindanao.

There are a number of radical fighters with alleged link to IS operating in the southern Philippines, including the BIFF, the Abu Sayyaf Group, and the Maute Group.

Abu Sayyaf and Maute militants co-plotted the siege of Marawi City in May 2017 that triggered a five-month fierce fighting between government forces and militants. The military claimed foreign terrorists also helped in plotting the Marawi siege that led to the death of at least 1,200.

Abu Sayyaf leader Isnilon Hapilon and Maute brothers Abdullah and Omar were killed, along with some 900 terrorists, as troops liberated Marawi in October 2017. New terrorist leaders emerged, including Abu Dar, who the army has described as IS' new chief in Southeast Asia.