US senator Marco Rubio has claimed that “something is off” with Vladimir Putin as invading Russian forces continued to attack Ukraine for the third day.

“I wish I could share more, but for now I can say it’s pretty obvious to many that something is off with #Putin,” Mr Rubio said on Twitter on Saturday.

“He [Putin] has always been a killer, but his problem now is different and significant. It would be a mistake to assume this Putin would react the same way he would have 5 years ago,” he said.

Mr Rubio is a member of the Senate intelligence committee that makes him privy to briefings from American spies.