ISLAMABAD: Suleman spent years targeting members of the Shia community in his home country of Pakistan as a member of sectarian terrorist group Lashkar-e-Jhangvi (LeJ). Now he is on his way to a new sectarian battleground, Syria, where he plans to join rebels battling President Bashar Assad's regime.

The short and stocky man, who identified himself using only his first name for fear of being targeted by authorities, is one of an increasing number of militants who have left Pakistan for Syria in recent months.

The fighters have contributed to a growing presence of extremists and complicated US efforts to help the rebels. Many fighters like Suleman believe they must help Syria's Sunni majority defeat Assad's Alawite regime.

The presence of religious extremists in Syria looms large over US efforts to help the rebels, especially when it comes to providing weapons that could end up in the hands of America's enemies. The extremists have also sparked infighting with more secular rebels concerned about their increasing power. Most of the foreign fighters in Syria are from Arab countries, including Al Qaeda militants from Iraq on the rebel side and Hezbollah fighters from Lebanon on the regime's side. The flow of militants from Pakistan adds a new element to that mix.

Pakistani Interior Ministry spokesman Omar Hamid Khan said provincial authorities throughout Pakistan deny that militants have left the country for Syria. But three Pakistani intelligence officials based in the tribal region that borders Afghanistan, as well as militants themselves, say the fighters leaving Pakistan for Syria include members of Al Qaeda, the Pakistani Taliban and the LeJ.

The fighters fall mainly into two categories. One includes foreign combatants from places like Uzbekistan, Turkmenistan and likely the Middle East who came to Pakistan's tribal region to fight US-led forces in neighbouring Afghanistan and are now heading to Syria because they view it as the most pressing battle, said the Pakistani intelligence officials, speaking on condition of anonymity because they were not authorised to talk to the media. This group includes members Al Qaeda who trained the Pakistani Taliban in areas such as bomb-making and are now moving on to the battlefield in Syria, said Pakistani Taliban fighters, speaking on condition of anonymity.

Neither the intelligence officials nor the Pakistani militants were able to provide the total number of fighters who have left the country for Syria, or the route they were taking to get to the Middle East. An activist based in northern Syria, Mohammad Kanaan, said there are Pakistanis fighting in his area but not in large numbers. ''Most … are Arab fighters from Tunisia, Algeria, Iraq and Saudi Arabia,'' he said Sunday. ''But we have seen Pakistanis and Afghans recently as well.''

The second group leaving Pakistan includes mostly domestic members of the Pakistani Taliban and LeJ who are heading to Syria, saying they are being so closely monitored by Pakistani authorities that it makes it difficult for them to carry out operations at home, said a Pakistani Taliban fighter who identified himself only as Hamza.

These militants are under surveillance because they have been detained previously in connection with attacks, or are on Pakistan's radar because of their importance in their organisations, Hamza said. The group includes Suleman, who was detained during a 2009 attack on an intelligence building in the eastern city of Lahore that killed at least 35 people. He was eventually released, he told the AP in an interview before leaving for Syria more than a week ago.

Suleman is one of about 70 militants who have been sent to Syria in the last two months by a network jointly run by the Pakistani Taliban and LJ, Hamza said. The militants came from various parts of Pakistan, including the provinces of Balochistan, Punjab and Khyber Pakhtunkhwa (KP), and the southern city of Karachi, Hamza said.

Another group of 40, including Hamza, is expected to leave in the coming weeks, he said. These militants are not going to fight with Jabhat al-Nusra, or the Nusra Front, the most powerful Islamic militant group in Syria, Hamza said. But he did not know which group they would join. The head of the network sending these militants is a former leJ leader named Usman Ghani, Hamza said.

Another key member is a Pakistani Taliban fighter named Alimullah Umry, who is sending fighters to Ghani from KP, Hamza said.The militants are traveling to Syria by various routes, and some are taking their families. The most closely watched are secretly taking speed boats from Balochistan's coast to the Omani capital of Muscat and then traveling onward to Syria, Hamza said.

Others are flying from Pakistan to various countries, including Sri Lanka, Bangladesh, the United Arab Emirates and Sudan, and then making their way to Syria. The financing is coming from sources in the United Arab Emirates and Bahrain, Hamza said. Suleman flew to Sudan with his wife and two children using fake passports, he said. He will leave his family in Sudan and then travel to Syria. There are families of other Pakistanis who have gone to Syria already living in Sudan and being taken care of, Suleman said. A member of Jamaat-e-Islami said a small number of its followers have also gone to fight in Syria, but not through any organised network. He spoke on condition of anonymity for fear of being persecuted by the government.