TRIPOLI (AFP) - Libyan leader Moamer Gaddafi vowed in an audio message aired by state television on Tuesday that he would never surrender as NATO-led warplanes pounded Tripoli with one of the heaviest bombardments so far. In the message, his first intervention since he appeared on state television on May 19, Gaddafi said that he was close to the bombing but was still resisting and called on his people to resist too. "Despite the bombings, we will never submit," Gaddafi said in the broadcast. "I am near the bombing but I am still resisting," he added. "Have no fear, onward, onward," the Libyan leader said, adding: "You will never be able to defeat us, an armed people." Shortly after the recording was broadcast, fresh air strikes hit the Libyan capital continuing a bombardment that had gone on throughout the day. An AFP correspondent heard eight loud explosions from the area around Gaddafi's compound in the late morning, followed by more than a dozen in the early afternoon. A plume of smoke rose over a barracks in the complex which was "once again targeted by NATO," government spokesman Mussa Ibrahim said. Journalists taken on an escorted tour of the bomb-damaged compound were shown a dead body, draped in a green Libyan flag, which Ibrahim said was among a number of casualties from the air strikes. Several buildings had been hit. Government officials said they included one of Gaddafi's offices, an administrative building and a power plant. The British defence ministry said the targets included a secret police headquarters in the heart of Tripoli and a major military installation on the outskirts. "The missions were flown as part of a coordinated series of precision attacks throughout the day and night by NATO aircraft targeting intelligence and military facilities in the Libyan capital," defence staff spokesman Major General Nick Pope said. US President Barack Obama said after talks with German Chancellor Angela Merkel that pressure on Gaddafi "will only continue to increase" until the Libyan leader steps down. "The chancellor and I have been clear. Gaddafi must step down and hand power to the Libyan people, and the pressure will only continue to increase until he does," Obama told reporters at the White House standing alongside the German leader. In Libya's second city Benghazi, President Dmitry Medvedev's envoy Mikhail Margelov met rebel leaders in the first trip by a top Russian official to their eastern stronghold. Margelov, Medvedev's African envoy, said Russia was prepared to provide financial support to the rebels but opposed any escalation of the conflict. "Air strikes don't solve problems. We are in favour of a political solution, not a military escalation," he said. The rebels said they were ready to receive Russian aid "tomorrow," but stressed that they would not enter any negotiations until Gaddafi stepped down. "The only message that he can deliver to Gaddafi as far as the rebellion is concerned is 'Leave'," rebel spokesman Mahmoud Shammam said. Margelov paid tribute to the rebel leaders he met, who included Mustafa Abdul Jalil, head of the National Transitional Council that controls eastern Libya. "These people are Libyan patriots, serious people who want to stop the bloodshed as quickly as possible," the RIA Novosti news agency quoted Margelov as saying. "They don't want the blood or the heads of their enemies but they are thinking about the future and the development of their country and that's positive." Margelov said Moscow was prepared to "facilitate dialogue between the two camps," but Foreign Minister Sergei Lavrov stressed Russia did not want to be the lead mediator. "We are not seeking to take on the main role when it comes to mediation in Libya," Lavrov told reporters on a visit to NATO member Norway. "We have said several times that the African Union has the main role." Moscow has expressed alarm as NATO's air campaign to enforce a UN-mandated no-fly zone to protect civilians entered a new phase with the deployment of British and French attack helicopters over the weekend. Beijing said that Chinese diplomats had also arrived in Benghazi to meet with members of the opposition. Russia and China, both permanent Security Council members, abstained from the UN Security Council vote in March that gave the go-ahead for international military action against Gaddafi's regime.