witter Inc (TWTR.N) and law enforcement authorities are investigating alleged threats made by Islamic State militants against the social media network's co-founder and other employees, the company said in reaction to media reports.

Islamic State supporters, in online posts on Sunday, called for attacks against Twitter and its "interests," including death threats, according to the online news media company Buzzfeed as well as the NBC news network.

"Our security team is investigating the veracity of these threats with relevant law enforcement officials," a representative for Twitter said in a statement on Monday. Buzzfeed first reported the story on Sunday.

One alleged threat was directed to Twitter co-founder Jack Dorsey, NBC reported. Dorsey didn't address or acknowledge the threats in his latest tweets on Sunday.

The messages were posted on an anonymous file-sharing website called Pastebin, according to the media reports.

"Your virtual war on us will cause a real war on you,” one post by Islamic State supporters said, according to Buzzfeed. "We told you from the beginning it's not your war, but you didn't get it and kept closing our accounts on Twitter, but we always come back."