Facebook on Wednesday banned ads on its flagship website and Instagram that claim widespread voting fraud, suggest US election results would be invalid, or which attack any method of voting.
The company announced the new rules in a blog post, adding to earlier restrictions on premature claims of election victory.
The move came a day after US President Donald Trump used the first televised debate with Democratic challenger Joe Biden to amplify his baseless claims that the November 3 presidential election will be "rigged".
Trump has been especially critical of mail-in ballots, and he cited a number of small unrelated incidents to argue that fraud was already happening at scale.
Facebook has been under fire for refusing to fact-check political ads more broadly and for rampant organic misinformation.
Citing hate speech rules, it also moved Wednesday to remove Trump campaign ads suggesting that immigrants could be a significant source of coronavirus infections.
Facebook said the new election ad prohibition would include those that "portray voting or census participation as useless/meaningless" or that "delegitimize any lawful method or process of voting or voting tabulation... as illegal, inherently fraudulent or corrupt".
Israel is poised to send troops into Rafah, the Gazan city it sees as the last bastion of Hamas, Israeli media reported on Wednesday, saying preparations were under way to evacuate war-displaced Palestinian civilians who have been sheltering there.
A Russian court on Wednesday ordered one of Defence Minister Sergei Shoigu's deputies be kept in custody on suspicion of taking bribes, the highest-profile corruption case since President Vladimir Putin sent troops into Ukraine in 2022.
Former Japanese Prime Minister Taro Aso, a senior figure in the country's ruling party, met with Donald Trump on Tuesday, becoming the latest US ally seeking to establish ties with the Republican presidential candidate.
Russian missiles damaged residential buildings and injured six people in Ukraine's second-largest city, Kharkiv, early on Wednesday, Governor Oleh Synehubov said on Telegram.
Five migrants died in an attempt to cross the English Channel from France to Britain in an overcrowded small boat on Tuesday, hours after Britain passed a bill to deport asylum seekers to Rwanda in a move to deter the dangerous journeys.