Australia's prime minister has criticised England fans for booing Steve Smith after he was felled by a 92mph bouncer during the second Ashes Test.

There was widespread concern when Smith suffered a horrifying blow to the neck from a fierce Jofra Archer delivery on day four at Lord's.

The batsman was persuaded to retire hurt after receiving treatment in the middle but returned to complete his innings little more than 40 minutes later.

On each occasion he was applauded warmly by most in attendance but there were some who jeered, a common reaction since his return from a ball-tampering ban.

Smith was then ruled out of the final day of the Test with delayed onset concussion.

He added: "The reality is at the time he didn't have a concussion.

"If we pulled every player out who had a head impact we'd be pulling out 80% of players who don't have concussion so that would be an overreaction.

"It's pretty clear for us. We've got a doctor there. He is an expert in this field and trained to pick up even the minor signs of concussion.

"He was very confident that Steve was fine. He didn't have concussion at the time so he was allowed to play.

"If we'd left him out of the game we would have been leaving him out for no reason other than what we saw on the field."

Cricket Australia said Smith had a "precautionary scan" on his neck on Sunday, which cleared him of any structural damage.

He returned to the team hotel to rest after the scan and "will continue to be reviewed on an ongoing basis", CA added.