Arnold Schwarzenegger has returned to social media following open heart surgery, telling fans "I'm back".

The 70-year-old Terminator actor and former California governor underwent a scheduled procedure to replace a valve on Thursday.

On Monday he told his 4.43 million followers on Twitter: "It's true: I'm back!"

He wrote: "I went to sleep expecting to wake up with a small incision and woke up with a big one - but guess what? I woke up, and that's something to be thankful for."

His spokesman Daniel Ketchell said his first words after regaining consciousness were of course, "I'm back."

The Hollywood star, who moved from Austria to America when he was 20, was an award-winning body-builder before becoming an actor and politician.

His career as an action hero took off with the box-office hit "Conan the Barbarian" in 1982 and he was propelled to superstardom in 1984 with "The Terminator".

He served as governor of California from 2003 to 2011.

He had surgery in 1997 to replace the same heart valve, while a motorcycle crash in 2001 left him with several broken ribs.

He has had a hip replaced and had rotatory cuff surgery in 2003.