McGregor has supported the Chas charity for seven years

The film star, who is to become an ambassador for Unicef UK after getting involved with the charity on his travels, said he felt "rejuvenated".

"I worked very hard last year, I was tired and wanted a change of scenery," he told the BBC's Breakfast with Frost.

"I'm ready to go back to work," said the star of the recent Star Wars films.

McGregor, who travelled through 12 countries with his friend and fellow actor Charlie Boorman over the summer, visited three Unicef projects in Mongolia, the Ukraine and Kazakhstan.

"The Unicef projects were the pinnacles of poignancy for us on the trip," he said.

"Ninety-nine per cent of people we met were enthusiastic, generous, and supportive - I was really struck by that, a really optimistic view of the world.

"It was difficult to get back to London and hear some of the terrible things happening elsewhere in the world," he added.

McGregor is father to Clara, aged eight, and two-year-old Esther.

He is also patron of the Children's Hospice Association Scotland (Chas) and has helped it raise nearly �10m.