NATO has stepped up a psychological campaign to force Gaddafi's troops to surrender their arms and return home. TRIPOLI: Pressure piled on Libyan leader Muammar Gaddafi Tuesday as sources said that his oil minister had defected, NATO jets pounded Tripoli and he was rebuked by Moscow. Libyan Oil Minister Shukri Ghanem, a veteran of Gaddafi's regime, has left Libya and is in neighboring Tunisia, a Tunisian government source said Tuesday. Ghanem, also the chairman of Libya's powerful national oil company, crossed the border by car on Saturday and is staying in a hotel in the southern tourist island of Djerba, the official said on condition of anonymity. “Shukri Ghanem has left Libya. He entered Tunisia by car on May 14 across the Ras Jedir border post,” the source said. “He is currently in a hotel at Djerba and he has not tried to contact the Tunisian authorities.” If it is confirmed the minister has left his post, he would be among the most senior officials to abandon Gaddafi's government amid an uprising that erupted in mid-February. Former foreign minister Mussa Kussa defected to Britain in March, leaving Libya via Tunisia. The airstrikes by NATO Tuesday set fire to a security services building and the headquarters of Libya's anti-corruption agency, both near Gaddafi's compound in the Libyan capital. Meanwhile NATO said Tuesday it has stepped up a psychological campaign to force Gaddafi's troops to surrender their arms and return home by broadcasting radio messages and air-dropping leaflets. The messages also encourage pro-Gaddafi troops and civilians to stay away from military installations being targeted for air strikes, said Wing Commander Mike Bracken. In Moscow, Russian Foreign Minister Sergei Lavrov said he held talks Tuesday with Gaddafi's envoys and had told Tripoli to obey the terms of UN resolutions on Libya. “We raised the issues that directly come out of our principal position aimed first and foremost at urgently ending bloodletting in Libya,” Lavrov said in televised remarks. “We raised an issue about the need for the Libyan leadership to explicitly embrace and begin the implementation of the UN Security Council resolutions in full.”