US social media giant Twitter says it will strengthen measures to prevent the spread of misinformation, including posts related to Russia's invasion of Ukraine.

Twitter introduced its crisis misinformation policy on Thursday.

The company will issue warning notices on posts including "false coverage or event reporting, or information that mischaracterizes conditions on the ground as a conflict evolves" and "demonstrably false or misleading allegations of war crimes or mass atrocities against specific populations."

Twitter said tweets that violate the policy will be hidden behind a warning notice which says, "This Tweet violated the Twitter Rules on sharing false or misleading info that might bring harm to crisis-affected populations."
Users will be required to click "view" to read the tweets, and will not be able to retweet or share them.

Twitter will work with experts and human rights groups to determine when to apply the warning, and plans to expand the policy to cover conflicts in other areas and large-scale natural disasters.

US entrepreneur Elon Musk, who plans to acquire Twitter, has said the company should not hamper free speech.