Piers Morgan, the newspaper editor turned television host, has announced he has left US network CNN, six months after his show was cancelled following plummeting ratings.

Piers, 49, joined the channel more than three years ago when he took over the prime-time slot from veteran host Larry King to host Piers Morgan Tonight, later renamed Piers Morgan Live.

The show launched in January 2011, but initial audiences of two million fell to around 270,000 and it was axed in March.

Piers, the former editor of the Daily Mirror, apparently remained on CNN's payroll as negotiations took place over what further role he might play at the network.

But he today said he had left the organisation after turning down a two-year deal from CNN boss Jeff Zucker to host 40 special interviews.

Announcing his departure on Twitter, Piers said: " Breaking news: I am no longer a CNN employee.

"I was offered a new 2-year deal by CNN boss Jeff Zucker to host 40 big interview 'specials'. But after considerable thought, I decided not to accept it - and to try pastures new.

"I had a fantastic time in my 4 years at CNN and have huge respect for Jeff and all the people who work there. Great company, great network."

His tenure on the CNN talk show was marked by his ardent criticism of America's stance on gun laws and his campaigning in favour of gun control, leading to high-profile clashes with opponents and hundreds of thousands of people signing a petition calling for him to be deported.

He marked his leaving CNN with a parting shot at America's pro-gun lobby, the National Rifle Association (NRA), saying: " I wouldn't crack the champagne open too quickly though, NRA - I haven't finished with you lot yet."

Posting a video of him engaging in a heated argument with pro-gun lobbyists on his show, Piers said: " I knew this kind of outburst wouldn't endear me to gun-loving Americans - but I'd do it all over again."

Piers, whose Twitter profile says "One day you're the cock of the walk, the next a feather duster", had previously said he would ''be taken out of CNN kicking and screaming''.

But today the ardent Arsenal fan appeared at ease with his departure, joking that the day after football's transfer deadline, "Ironically, my transfer window just opened .... CNN".

Fellow celebrities have taken to social media to air their views on his move, with Match Of The Day pundit Gary Lineker tweeting: "See you've finally parted company with CNN, Piers Morgan. We'll really miss you ..... being over there!"

A CNN spokesman said: "We wish Piers all the best."