Karzai cancels press conference after anti-American rant A joint press conference at Mr Karzai's palace was then cancelled. Mr Karzai's palace said there were "scheduling problems." US officials said there were security concerns and the conference had not been cancelled because of Mr Karzai's comments. They were still due to meet in private. Mr Hagel arrived on Friday to visit some of America's 66,000 troops in Afghanistan and his trip has since been beset by incident. A Taliban suicide bomber killed nine outside the Afghan ministry of defence on Saturday in an attack the insurgents claimed was a message to Mr Hagel that their strength was undiminished. Another bomber killed nine, mainly children, in Khost. American tensions with Kabul were also strained when a handover ceremony to mark the final transfer of Bagram US military prison to Afghan control was cancelled at the last minute. The deal fell through amid American concerns that dangerous Taliban prisoners would be freed to return to the battlefield as soon as the maximum security jail was given over to Kabul's custody. Speaking on Sunday morning, Mr Karzai said the weekend's bombings by insurgents were "not aimed at showing their strength to the USA but to serve the USA." "Yesterday's bombings in the name of the Taliban were aimed at serving the foreigners and supporting the presence of the foreigners in Afghanistan and keeping them in Afghanistan, by intimidating us," he said. America was holding talks with the Taliban "every day" in the Gulf and Europe, he said. Both America and the Taliban rejected Mr Karzai's comments. "This is simply incorrect," said a US government official. In late 2011 Taliban envoys met US officials in the Gulf and expressed interest in opening a political office in Doha as a venue to help start a peace process. The initiative collapsed a year ago, but many of the Taliban envoys are believed to remain in the Gulf.