The San Francisco-based social network also said it would not allow people to use software to simultaneously perform other actions such as liking or retweeting from multiple accounts.

Twitter, known for freewheeling discussions in short messages, is under pressure from users and Western governments to stem the spread of false news and foreign propaganda, often done with the help of automated accounts known as bots.

Twitter bots disseminated propaganda before the 2016 US elections and have continued to inflame US politics under cover of anonymity, academic researchers and US authorities said.

On Friday, the office of US Special Counsel Robert Mueller charged 13 Russians and three Russian companies, including St. Petersburg-based Internet Research Agency known for trolling on social media.

The court document said those accused "had a strategic goal to sow discord in the US political system, including the 2016 US presidential election."

Twitter's new restrictions were aimed at improving "information quality," Yoel Roth of the company's policy team said.

"These changes are an important step in ensuring we stay ahead of malicious activity targeting the crucial conversations taking place on Twitter - including elections in the United States and around the world," Roth said in a statement.

Posting identical messages to multiple accounts, or simultaneously retweeting or liking a message from multiple accounts, could help vault something into Twitter's trending list, giving a false impression of how viral it is among real people.

Twitter said it would give users until March 23 to comply before suspending accounts. It made an exception for bots of broad interest such as earthquake alerts.

Twitter also cracked down on other violations of its terms of service, including fake accounts by people inflating their following.

Australian Associated Press