London: Pakistan Prime Minister Nawaz Sharif has said that reports were still not confirmed that Taliban leader Mullah Mansour was killed during a US drone strike. He spoke to media after arriving in London, the prime minister however confirmed that he had received a phone call from US Secretary of State John Kerry, reports Geo. Kerry had informed him about the drone attack, he added, but maintained that he was informed about the strike after it had been conducted. "Afterwards, I spoke with the army chief as well," he said. Sharif also said that the foreign office's statement was a protest against the drone attack. Meanwhile, the Pakistani Foreign Ministry has said that a passport found at the site of a US drone attack targeting Afghan Taliban leader Mullah Akhtar Mansour bears the name of a Pakistani man named Wali Muhammad. The purported passport holder was believed to have returned to Pakistan from Iran on May 21, the day of the drone strike targeting Mansour. One of the charred bodies has been identified as a local taxi driver but the badly burnt second body was yet to be. The ministry spokesman called the attack a violation of Pakistan's sovereignty.