Fresh fighting has broken out in the Libyan capital, Tripoli, hours after Col Gaddafi's son and his presumed successor, Seif al-Islam appeared in the city saying the government was still in control. Heavy fighting took place on Tuesday near Gaddafi's Bab al-Aziziya compound, gunfire and explosions shook several parts of the city, which the rebels claim to have mostly under their control. The International Criminal Court on Tuesday disputed reports that it had confirmed Seif al-Islam's detention, saying the court never received official word from the opposition Transitional National Council.Senior rebel sources also said another of Mr. Gaddafi's sons, Mohammed, escaped house arrest on Sunday. A third son is apparently still in detention and Col. Gaddafi's whereabouts are unknown. Meanwhile, the International Organization for Migration on Monday said the fighting in Tripoli has forced it to delay docking a boat to begin evacuating stranded migrants. The group says the boat, which can carry 300 people, will remain off shore until the security situation improves.On Sunday, the rebels broke through Tripoli's outer defenses and reached the city's central Green Square. They moved into central Tripoli with little resistance after capturing a key military base run by the government's elite Khamis Brigade and commanded by another son of Col. Gaddafi.