(Releads with explosion in Beirut) By Nadim Ladki BEIRUT, June 13 (Reuters) - An explosion rocked Beirut's seafront corniche on Wednesday, killing at least four people near a military beach club, security sources said. They said several people were wounded in the blast which tore through a street near an amusement park and the Bain Militaire sporting club. Television pictures showed a car ablaze and shattered windows of a nearby restaurant. The explosion was the latest in a series of recent bombings in Lebanon, where the army is battling Islamist militants at a Palestinian refugee camp in the north of the country. Two Lebanese soldiers were killed in fresh fighting at the Nahr al-Bared camp on Wednesday, security sources said. Al Qaeda-inspired Fatah al-Islam militants attacked Lebanese army posts set up at newly seized territory in the outskirts of Nahr al-Bared camp overnight and in early morning, they said. One of the dead was an officer shot by a sniper, they said. Army units, which had seized two militant positions in heavy fighting on Tuesday, responded by firing dozens of 155 mm artillery rounds at the camp. Black smoke rose above the camp's cinderblock buildings as thuds of explosions rocked the area. The battle for the camp, Lebanon's bloodiest internal violence since the 1975-1990 civil war, has killed 144 people, including 62 soldiers, more than 50 militants and 32 civilians, since it erupted on May 20. The Lebanese authorities have demanded the unconditional surrender of the gunmen, who have vowed to fight to the death. Fatah al-Islam was officially formed late last year. Its leader, veteran Palestinian guerrilla Shaker al-Abssi, says he shares the same ideology as al Qaeda but has no organisational links with that group. Many of his men are foreign Arab fighters, some of whom have fought in Iraq. Most of Nahr al-Bared's estimated 40,000 refugees fled to other camps in the early days of the battle. But a few hundreds more have left in recent days. Lebanese soldiers have been questioning the men leaving the camp to make sure there were no militants among them trying to slip through, security sources said. Human Rights Watch said in a statement released in Beirut the security forces were detaining and physically abusing some Palestinian men fleeing the camp. It quoted some of them speaking of beatings and food deprivation. "Lebanese forces can question Palestinians from Nahr al-Bared about Fatah al-Islam, but resorting to physical abuse is clearly against Lebanese law and international human rights standards," said Sarah Leah Whitson, Middle East director of Human Rights Watch.
