US news anchor loses the plot during ad break in leaked video

Lawrence O'Donnell lost the plot during the ad-break of his show.
Lawrence O'Donnell lost the plot during the ad-break of his show. Photo credit: Mediaite

A US news anchor has apologised after an eight-minute tirade while preparing for his show leaked online.

MSNBC host Lawrence O'Donnell can be seen throwing pens and paper, berating his staff and swearing in the clip, frustrated that he can hear someone in his earpiece during the ad breaks of his show.

"Who's asking for a Labour Day rundown in my ear?" he yells at his staff, who wisely keep their heads down as they walk past.

"Someone in the control room is out of control. F**k sake. You have insanity in my earpiece."

Shortly after, he completely loses the plot when he hears a hammer outside.

"Stop the hammering, who's got a hammer out there? Who is it?

"I'll go down to the goddamn floor myself and stop it.

"Call f**king [MSNBC president] Phil Griffin, I don't care who you have to call, stop the hammering. Clear out the control room.

"This f**king stupid hammering. It just f**king sucks to be out here with this out of control shit."

The eight-minute clip was obtained by website Mediaite, and has been shared widely since.

Mr Lawrence has since apologised for his anger, which is a far cry from his calm on-air demeanour.

"A better anchorman and a better person would've had a better reaction to technical difficulties. I'm sorry," he wrote on Twitter.

It is still unclear who had the hammer.