Hamas politburo chief Ismail Haniyeh has been killed in Tehran, confirmed Hamas and Iran's Islamic Revolution Guards Corps (IRGC) in separate statements early on Wednesday.

Haniyeh was in Tehran attending Iran's new president's swearing in ceremony on Tuesday.

"Early this morning, the residence of Ismail Haniyeh in Tehran was struck, resulting in his and one of his bodyguards' martyrdom. The cause is under investigation and will be announced soon," the Revolutionary Guards said.

A Hamas official called the assassination a "grave escalation" and said that it would not achieve its goals, according to Reuters report.

(Cover: File photo of Hamas politburo chief Ismail Haniyeh. /CFP)