WASHINGTON (Reuters) - The Trump administration has determined that China has committed “genocide and crimes against humanity” by repressing Uighur Muslims in its Xinjiang region, Secretary of State Mike Pompeo said on Tuesday, delivering an embarrassing blow to Beijing a day before U.S. President-elect Joe Biden is set to take office. Pompeo said he made the move - which is certain to strain further already frayed ties between the world’s top economies - “after careful examination of the available facts,” accusing the Chinese Communist Party of crimes against humanity against the Uighurs and other Muslim minorities since at least March 2017. “I believe this genocide is ongoing, and that we are witnessing the systematic attempt to destroy Uighurs by the Chinese party-state,” Pompeo said in a statement. China has been widely condemned for its Xinjiang complexes, which it describes as “vocational training centers” to stamp out extremism. It denies accusations of abuse. The rare U.S. determination follows intensive internal debate after Congress passed legislation on Dec. 27 requiring the U.S. administration to determine within 90 days if China had committed crimes against humanity or a genocide. Biden’s campaign declared, before the Nov. 3 U.S. election, that genocide was occurring in Xinjiang. Biden’s transition did not immediately comment on Pompeo’s announcement. China’s Embassy in Washington also did not immediately respond to a request for comment, but last week rejected as “lies” a congressional report that said “crimes against humanity - and possibly genocide - are occurring” in Xinjiang. U.S.-China ties plummeted to their lowest level in decades during President Donald Trump’s administration and the genocide declaration will ensure an especially difficult start to the Biden’s administration’s relationship with Beijing. Daniel Russel, a Biden campaign adviser and a top Asia official under Trump’s predecessor President Barack Obama, called Pompeo’s move “the height of cynicism” and an an attempt to lay “a malicious political booby-trap” for Biden. ACCOUNTABILITY The U.S. decision does not automatically trigger any penalties, but means countries will have to think hard about allowing companies to do business with Xinjiang, a leading global supplier of cotton. Last week Washington imposed a ban on all cotton and tomato products from Xinjiang. In his statement, Pompeo called “on all appropriate multilateral and relevant juridical bodies, to join the United States in our effort to promote accountability for those responsible for these atrocities.” The International Criminal Court can investigate crimes of genocide, war crimes, crimes against humanity, but China - like the United States - is not a court member, so the situation in Xinjiang would have to be referred by the U.N. Security Council, where China could veto such a move. An independent U.N. human rights panel said in 2018 that it had received credible reports that at least 1 million Uighurs and other Muslims had been detained in Xinjiang. Faith leaders, and activists have said crimes against humanity, including genocide, are taking place. In the past 30 years, the U.S. State Department has declared a genocide occurred in at least five situations - Bosnia in 1993, Rwanda in 1994, Iraq in 1995, Darfur, Sudan in 2004, and in areas under Islamic State control in Iraq in 2016 and 2017. U.S. officials said Pompeo viewed a lot of open-source reporting and evidence before making Tuesday’s declaration, but did not provide specific examples. Pompeo last year referred to a report by German researcher Adrian Zenz that China was using forced sterilization, forced abortion and coercive family planning against Muslims. His decision prompted criticism from opponents, who described it as a purely political move, citing the Trump administration’s reluctance to make the same determination for atrocities committed against Rohingya Muslims in Myanmar. Under international law, crimes against humanity are defined as widespread and systematic, whereas the burden of proof for genocide - the intent to destroy part of a population - can be more difficult to prove.