By Steve Holland and Michelle Nichols
WASHINGTON/UNITED NATIONS, Sept 20 (Reuters) - U.S. President Donald Trump will tout U.S. leadership and a collective approach to challenges while at the United Nations next week, said a senior administration official on Friday, as Washington seeks to use the gathering of world leaders to build support to take on Iran and call out China over rights abuses.
While Trump has questioned the value of the United Nations and scorned the importance of multilateralism as he focuses on an "America First" agenda, he will return for a third time to push religious freedom on Monday, address the General Assembly on Tuesday and discuss Venezuela on Wednesday.
"Obviously our overarching concern with Iran's escalatory violence is going to be a theme," the official said, speaking on condition of anonymity. "We welcome opportunities to discuss collective response."
The United States and its ally Saudi Arabia blame Iran for an attack last Saturday on the world's biggest crude oil processing facility and have said they will present evidence to back that up. Iran denies involvement in the attack. Yemen's Iran-aligned Houthi group, which has been fighting a Saudi-led military coalition since 2015, has claimed responsibility.
Trump has said he is considering how to respond and that military action is an option. The United States on Friday imposed another round of sanctions on Tehran.
Iranian President Hassan Rouhani is due to address the United Nations on Wednesday.
Last week Trump flirted with meeting Rouhani, but has since backed away from the idea. Iran's Supreme Leader Ayatollah Ali Khamenei has said Iran would never hold such one-on-one talks but could engage in multilateral discussions if Washington returns to a 2015 nuclear pact.
Trump will meet at least a dozen leaders during his three days in New York.
U.N. Secretary-General Antonio Guterres has made climate action his priority with a summit dedicated to tackling the crisis on Monday. But Trump is skeptical of global warming and he and U.S. Vice President Mike Pence will host an event at the same time on religious freedom.
While it is not clear if Trump or Pence will make reference to any specific situations, U.S. Deputy Secretary of State John Sullivan will host a separate event on Tuesday on the "human rights crisis in Xinjiang" in China, diplomats said.
The United Nations says at least 1 million ethnic Uighurs and other Muslims have been detained in Xinjiang. Beijing describes complexes in Xinjiang as "vocational training centers" helping to stamp out extremism and give people new skills.
"We know that some country is trying to make a fuss on issues relating to China, including the situation in Xinjiang," China's U.N. Ambassador Zhang Jun said on Friday.
"If they simply want to make the issue a political issue, definitely we have every right to defend ourselves and we are completely opposed to any such interference in China's internal affairs," Zhang said.
Trump drew gasps during his first speech to the 193-member United Nations in 2017 with a threat to wipe out North Korea and then laughter last year with a boast about the achievements of his administration.
Though not specifically addressing Trump's speech on Tuesday, the administration official said he would "affirm America's leadership role in the rules-based international system, and the need to work collectively within the global community to address global challenges."
Trump would also assert "America's determination to uphold the sovereignty and independence of member states especially on issues of national security," the official said.
The message is being delivered at a time when some diplomats say U.S. leadership in global institutions is waning and China's influence is growing. Since Trump took office, he has quit the U.N. Human Rights Council, the U.N. cultural agency UNESCO, a global accord to tackle climate change, the Iran nuclear deal and opposed a U.N. migration pact.
"We do think the United States will – in one way or another – come back to the right track because they will realize ... going back to multilateralism, going back to international cooperation does serve the fundamental interest of the United States," China's U.N. envoy Zhang said on Friday.
He told reporters the United Nations was at a crossroads and that the "biggest challenge facing the world is a deficit of trust, especially a deficit among major players."
The Chinese government's top diplomat, State Councillor Wang Yi, is due to address the United Nations next week, when more than 135 presidents and prime ministers and dozens of ministers were expected to attend the 74th U.N. General Assembly.
A senior U.N. official, speaking on condition of anonymity, said on Friday: "Even though everyone says that multilateralism is dead, multilateralism isn't very popular these days, countries are becoming more and more isolationist – everybody comes." (Reporting by Steve Holland in Washington and Michelle Nichols at the United Nations; editing by Mary Milliken and Grant McCool)