Islamic State supporters have celebrated on social media after a blast at a Manchester concert venue killed at least 19 people, although the militant Islamist group has not formally claimed responsibility.
British police have said they are treating the blast at the Manchester Arena at the end of a concert by US singer Ariana Grande as a "terrorist incident".
More than 50 people were wounded. Twitter accounts affiliated to IS have used hashtags referring to the blast to post celebratory messages, with some users encouraging similar attacks elsewhere.
Some messages described the attack as an act of revenge in response to air strikes in Iraq and Syria. One user said he hoped Islamic State was responsible for the attack, although no claim has appeared on any of the militant's group's official social media channels.
"We hope that the perpetrator is one of the soldiers of the caliphate," he wrote on a channel affiliated to the group hosted by messaging network Telegram.
