A Twitter row has broken out between the US and Chinese ambassadors to Brazil in an echo of the tense relations between their countries. It started on Friday, with a retweet by US ambassador Todd Chapman of a State Department account which accused China’s Communist Party of conducting a “mass sterilisation campaign for women as part of its crackdown on Uygurs and other ethnic minorities” in Xinjiang . “Silence is not an option,” Chapman said. On Saturday, the US embassy’s Twitter account quoted FBI director Christopher Wray accusing China of paying scientists at American universities “to secretly bring our knowledge and innovation back to China – including valuable research, funded by the federal government”. It added: “Is this happening in Brazil?” China-Brazil trade on track, but Huawei tension may threaten relations Chinese ambassador Yang Wanming reacted on Sunday, with a tweet which read “this man comes to Brazil with a special mission, which is to attack China with rumours and lies. We advise you to stop doing activities of this kind … An ant tries to knock down a giant tree, ridiculously exaggerating its ability.” It was a small echo of a larger dispute. China’s government said on Friday it would retaliate against US officials and institutions following Washington’s imposition of sanctions on three local officials of the ruling Communist Party over human rights abuses in the northwestern region of Xinjiang. Brazil and the US are strongly aligned. On July 4, shortly before testing positive for Covid-19, the disease caused by the new coronavirus , Brazilian President Jair Bolsonaro was with Chapman to celebrate US Independence Day. In March, Congressman Eduardo Bolsonaro, the president’s son, blamed China for the pandemic, prompting the Chinese ambassador to respond that his words were “an evil insult against China and the Chinese people”.