Australian actor Sullivan Stapleton suffered a nasty head injury when he fell out of a tuk-tuk in Thailand and is expected to be out of action for up to six months.

The star was filming U.S. Tv series Strike Back in the country when he sustained a mystery injury. The shoot was put on hiatus and the actor had to drop out of the publicity tour for his new blockbuster movie 300: Rise of an Empire.

Stapleton has now revealed he fell out of an automatic rickshaw - also known as a tuk-tuk - during a night out and suffered a worrying head injury.

He tells Australia's Herald Sun, "We'd been out and I fell off the tuk-tuk and my head hit the ground and it was quite serious... a lot more serious than I initially thought."

Despite the injury, he was more concerned about missing work, saying, "Missing out on the publicity tour (for 300: Rise of an Empire) was definitely disappointing, especially as the film is going so well."