US President Barack Obama expressed his condolences over the missing Chinese aboard a Malaysia Airlines flight in a telephone conversation with President Xi Jinping yesterday. Obama also said the US was ready to co-operate with China on combating terrorism, according to the foreign ministry. In the conversation, which came as the two leaders prepare to meet at a nuclear summit next month, Obama said the US was ready to work with China in the search efforts for flight MH370, which went missing with 239 aboard. Two-thirds of the passengers were Chinese nationals. Xi told Obama China had instructed relevant authorities to carry out search and rescue operations. Obama also told Xi the US was "against all forms of terrorism and stood ready to co-operate with China in the fight against terrorism", a reference to the March 1 attack at a train station in Kunming , Yunnan province, in which 33 people died, including four attackers. In response, Xi said China was prepared to work with the US in combating terror. The two presidents also agreed a peaceful solution was needed in Ukraine. "They affirmed their shared interest in reducing tensions and identifying a peaceful resolution to the dispute between Russia and Ukraine," a White House statement said. Xi called on all parties concerned to exercise restraint to prevent tensions from escalating. The two leaders last met on the sidelines of a G20 summit in Russia in September. They were due to meet in a major regional summit in Indonesia last October, but Obama cancelled his Asia trip because of the fiscal crisis in the US. They are due to meet next at the nuclear summit in the Netherlands next month. Beijing's relations with Washington have been strained since Obama announced the US pivot towards Asia. China also expressed its displeasure over the American president's decision to meet the Dalai Lama at the White House last month. Su Hao, a professor with the China Foreign Affairs University, said the anti-terrorism effort was common ground upon which the two nations could work together amid wider mutual suspicions. "Both nations expect support from each other in their anti- terrorism campaigns," Su said. "If the missing flight incident is confirmed as a terror attack, the nations may need to strengthen co-operation to maintain security in Southeast Asia." Jin Canrong, a US affairs expert at Renmin University, said Beijing was emphasising that both the US and China faced terrorism threats, and China might seek Washington's help in intelligence-gathering and security personnel training.