Social media giants Facebook and Twitter have not detected Chinese meddling in the 2018 elections, company officials said, casting doubt on claims by President Donald Trump that Beijing is trying to interfere. The companies have reported online disinformation campaigns before the November 6 elections that appear to originate from Russia and Iran. But press representatives for both firms, who spoke on condition of anonymity, said they have not found evidence of such activity from China. Facebook and Twitter are the latest in a string of tech companies to dispute Trump’s claim. China has been attempting to interfere in our upcoming 2018 election … against my administration US President Donald Trump Last week, top cybersecurity firms – FireEye, Symantec and Crowdstrike – said they have not seen evidence of digital interference by China . In the wake of alleged Russian interference in the 2016 election, Facebook and Twitter have stepped up efforts to detect and stop disinformation campaigns by foreign governments on their platforms. The companies use automated algorithms and human reviews of suspicious activity to search for coordinated campaigns. Facebook and Twitter have both suspended or removed accounts that appeared to come from Russia and Iran and seemed intended to influence US opinion. The Trump administration’s claims about Chinese interference have mounted since last month, when he told the United Nations Security Council: “China has been attempting to interfere in our upcoming 2018 election … against my administration.” Vice-President Mike Pence echoed that up this month, saying: “There can be no doubt: China is meddling in America’s democracy.” Trump threatens fresh China tariffs as he claims Beijing’s meddling is worse than Russia’s Pence insisted Beijing’s behaviour was “an unprecedented effort to influence American public opinion, the 2018 elections and the environment leading into the 2020 presidential elections”. Trump and Pence cited a paid advertising supplement the Chinese government placed in The Des Moines Register , Iowa’s largest newspaper, criticising the administration’s trade policies. China is actually placing propaganda ads in the Des Moines Register and other papers, made to look like news. That’s because we are beating them on Trade, opening markets, and the farmers will make a fortune when this is over! pic.twitter.com/ppdvTX7oz1 — Donald J. Trump (@realDonaldTrump) September 26, 2018 <!--//--><![CDATA[// ><!--\n\n\n//--><!]]> Beijing and Washington are currently locked in an escalating trade war and late last month, US and Chinese warships nearly collided in the South China Sea , where both nations are trying to assert their regional dominance. The Department of Homeland Security, Federal Bureau of Investigation and Office of Director of National Intelligence warned last Friday that nations including China were engaged in “ongoing campaigns” to “undermine confidence” and influence policy and opinion in the US. The administration has not provided any evidence to back up the claims.