TEHRAN: President Hassan Rouhani was headed for New York on Monday to attend the UN General Assembly on a mission to win support for Iran against "cruel" pressure from its arch-foe the United States.His departure came as Tehran said an oil tanker flying the flag of US ally Britain was "free" to leave more than two months after seizing it in sensitive Gulf waters.Before departing, Rouhani said his delegation was heading to the UN gathering despite Washington´s reluctance to issue them US visas. Tehran and Washington have been at loggerheads since May last year when President Donald Trump abandoned a 2015 nuclear deal and subsequently began re-imposing sanctions on Iran in a stated campaign of "maximum pressure"."It is essential for us to take part in the UN General Assembly and talk at various levels," Rouhani said at Tehran´s Mehrabad airport. "The cruel actions that have been taken against the Iranian nation and also the difficult and complicated issues that our region faces with them need to be explained.”Britain´s Prime Minister Boris Johnson said Monday that his government was drawing a similar conclusion. “The UK is attributing responsibility with a very high degree of probability to Iran” for the Saudi attacks, he said, quoted by Britain´s PA news agency. Johnson was himself en route to New York, where he was scheduled to meet with Rouhani.Iran slammed Britain over the accusation. “Instead of fruitless efforts against the Islamic Republic of Iran, Britain must stop selling deadly weapons to Saudi Arabia and free itself from accusations of committing war crimes against Yemenis,” foreign ministry spokesman Abbas Mousavi said, quoted by Tasnim news agency.Iran´s government spokesman Ali Rabiei said Monday the tanker was “free” to leave after the completion of legal proceedings, without specifying when it might set sail. The announcement comes after a court in British overseas territory Gibraltar ordered the release of an Iranian oil tanker in mid-August.Before flying to New York, Rouhani said Iran would put forward a Gulf peace plan at the UN meeting.The US has said it would make its case against Iran at the UN. Secretary of State Mike Pompeo said the US wanted to give diplomacy “every opportunity to succeed” in the wake of the Saudi attacks.Iran on Monday reiterated its conditions for any talks with the US. “If the US is ready to end sanctions and come back to the conditions of the nuclear agreement, the way would be open for us to make a decision,” said Rabiei.