Hollywood star Tom Hanks opened the London Film Festival on Wednesday with his new film "Captain Phillips", based on the true story of a ship attacked by Somali pirates.

The 57-year-old will also close the festival playing Walt Disney in new release "Saving Mr Banks", which dramatises the making of the Wizard of Oz.

Hanks is being talked about as an Oscar candidate for his depiction of Phillips, who was the captain on board container ship Maersk Alabama when it was hijacked 2009.

Phillips was taken hostage with his crewmates, and it is Hanks' performance in the final minutes of the film, directed by Briton Paul Greengrass, which has critics raving.

But the Forrest Gump star would not reveal how he was able to muster such powerful emotion.

"It's a secret," he explained at a press conference. "It's like going to a Coca-Cola press conference and asking for their secret formula."

"I'm a professional and I like to think of myself as a creative artist and you sort of take that on," said the double-Oscar winner.

"As soon as you say yes to something you realise that a day is going to come where you have to be in a place that is both manufactured and yet very real to all your senses. And you prepare to get there as best you can, and when the time comes hopefully you achieve it."

Hanks will end the festival on a much lighter note playing movie-mogul Disney.

The biographical film, directed by American John Lee Hancock, portrays Disney's dogged efforts to convince Mary Poppins author Pamela Lyndon Travers to adapt the book for the big screen.

In between the double dose of Tom Hanks, the festival, which runs until October 20, will present 232 feature-films and a procession of stars including Sandra Bullock, Judi Dench, Carey Mulligan, Colin Farrell, Ralph Fiennes, Kate Winslet and Emma Thompson.

Another highlight will be the appearance of Mexican director Alfonso Cuaron, who will explain the process of making 100 million euro film "Gravity" -- starring Bullock and George Clooney -- which is also tipped for Oscars honours.