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".
US President Donald Trump said an angry Israel "violently lashed out" and attacked Iran's major gas field, a significant escalation in the US-Israeli war, but ruled out further such attacks by Israel unless Iran retaliated further.
Israel reopened the Rafah crossing with Egypt on Thursday after nearly three weeks to allow some wounded Palestinians to leave for treatment, after Gaza medics said Israeli strikes had killed four people in the enclave.
Saudi Arabia reserves the right to act militarily against Iran and any trust with Tehran has been shattered, the Saudi foreign minister Prince Faisal bin Fahran said early on Thursday, after Riyadh was targeted by Iranian ballistic missiles.
Kuwait Petroleum Corporation says one of the operational units at the Mina Al Ahmadi refinery was hit on Thursday by a drone, resulting in a "limited" fire.