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".
Spain and Portugal switched their power back on after the worst blackout in their history, though authorities offered little explanation for what had caused it or how they would prevent it from happening again.
The head of Israel's domestic intelligence agency, Ronen Bar, announced he will resign on June 15 amid pressure from Prime Minister Netanyahu and ongoing legal proceedings.
In the chaotic first 100 days since President Donald Trump returned to office, he has waged an often unpredictable campaign that has upended parts of the rules-based world order that Washington helped build from the ashes of World War II.
Canadian Prime Minister Mark Carney's Liberals retained power in the country's election on Monday, but fell short of the majority government he had wanted to help him negotiate tariffs with US President Donald Trump.
A huge power outage hit large parts of Spain and Portugal on Monday, paralysing traffic, grounding flights, trapping people in elevators and leaving power operators scrambling to restore power to millions of homes and businesses.
Russian President Vladimir Putin on Monday declared a three-day ceasefire in the war with Ukraine next month to mark the 80th anniversary of the victory of the Soviet Union and its allies in World War II.