TRIPOLI (Reuters/AFP) - Tripoli struggled with collapsing water and power supplies on Saturday as rebels now in control of most of the Libyan capital vowed to take Muammar Gaddafi's home town by force if negotiations failed. More evidence emerged of summary killings during the battle for Tripoli, which erupted a week ago. A correspondent for Britain's Sky News said he had counted about 53 bodies left in a burned-out warehouse, where they were apparently executed earlier this week. "It is a scene of mass murder," Stuart Ramsay said at the scene, quoting witnesses as saying 150 people were killed there on August 23 and 24 as rebel fighters fought pro-Gaddafi forces. A local resident told Sky the victims were mostly civilians and had been killed by Gaddafi's forces. Reports of cold-blooded killings by both sides have surfaced in the last few days, darkening the atmosphere in a city where many residents had greeted Gaddafi's fall with joy. Gaddafi's own whereabouts remain unknown - rebels hunting him say the war will not end until the 69-year-old colonel who kept Libya in his grip for 42 years is captured or killed. Mustafa Abdel Jalil, head of the rebel National Transitional Council (NTC), told reporters in Benghazi: "We have no factual report about the whereabouts of Gaddafi and his sons." The NTC, which has told its fighters not to carry out revenge killings, is trying to assert its authority and restore order in Tripoli but its top officials have yet to move there from their Benghazi headquarters in the east. Rebel commanders are still negotiating with Gaddafi loyalists to try to persuade them to surrender control over the coastal city of Sirte, Gaddafi's home town, Abdel Jalil said. Ahmed Jalil promised Saturday that Moamer Gaddafi and officials of his regime would be given a fair trial. Rebels said they captured the last military base held by forces loyal to strongman Moamer Gaddafi in the Tripoli area on Saturday. "NATO struck and then our special forces attacked," fighter Nurdin Yussef Misrata, 36, who took part in a dawn assault on the base of 32 Brigade commanded by Khamis Khadafi, a son of the leader, told AFP. German Chancellor Angela Merkel was quoted telling a newspaper on Saturday that she would like to see Libya's fallen leader Muammar Gaddafi put on trial - even though he never gave his opponents a chance to defend themselves in court. The International Criminal Court has indicted Gaddafi and issued arrest warrants in June for him, his son Saif al-Islam and Libyan intelligence chief Abdullah al-Senussi on charges of crimes against humanity for their role in the killing of civilian protesters at the start of a six-month uprising. Libya is effectively cut in two by pro-Gaddafi forces holding territory stretching southwards from Sirte, 450 km (300 miles) east of the capital, deep into the desert. A rebel commander said forces advancing from the east had reached the edge of Bin Jawad, a town about 140 km from Sirte. "We are waiting for the people in Sirte to come out and talk but we've got no answer up to now. I've been waiting for three days," the commander, Fawzi Bukatif, told Reuters, adding that Sirte must be taken eventually by force or peaceful means. With rebel forces approaching from east and west, Gaddafi loyalists in Sirte could retreat into the desert and try to reach Sabha, another Gaddafi stronghold far to the south. "If they pull south to Sabha, we'll follow them. We're determined to clear the whole country," said Bukatif.