A bomb concealed in a motorcycle exploded Tuesday near a mosque in a south Lebanon Palestinian refugee camp, killing a militant and lightly wounding four people, Lebanese and Palestinian security officials said. The attack occurred in the afternoon as militant Ahmad Mustafa Qassem walked near the Al-Nour Mosque. He was instantly killed, the officials said. Qassem was a member of the Islamic Struggle Movement, a small group based in the Ein El-Hilweh refugee camp on the outskirts of the city of Sidon. Ein El-Hilweh has in recent weeks seen clashes and assassinations between members of Palestinian President Mahmoud Abbas' Fatah group and militants from Jund al-Sham, a group that follows the extremist ideology of Al-Qaeda. The Leader of the Islamic Struggle Movement, Sheik Jamal Khattab, told Al-Manar television of the militant Hezbollah group that Qassem was praying at the mosque minutes before he was killed. Khattab, also the imam of the Al-Nour mosque, did not say if Qassem was a member of his group. The Palestinian and Lebanese security officials spoke on condition of anonymity because they were not authorized to speak to the media. Ein El-Hilweh, with a population of 70,000, is the largest of Lebanon's 12 Palestinian refugee camps and is a hotbed of Islamic extremists. ‘Syrian troops on border' Syria has deployed troops near Lebanon's northern border in an attempt to crack down on smugglers, a senior Lebanese military official said Tuesday. The official said the deployment has nothing to do with security developments in Lebanon. Syrian President Bashar Assad recently warned that “extremist forces” – a reference to Sunni militants – were operating in northern Lebanon and destabilizing the country. “The Syrian army is carrying out activities to combat smuggling and control the border,” the Lebanese official told The Associated Press. “It is an internal Syrian affair and is not connected with developments in Lebanon,” he said. The Lebanese official declined to disclose the number of troops deployed on the northern border, but he dismissed as “exaggerated and inaccurate” press reports that 10,000 were involved.