Peter Jackson's $200m remake of King Kong took in an estimated $18m worldwide on its opening day, according to studio estimates.

Distributor Universal Studios said the film earned about $9.8m at the US and Canadian box office when it debuted Wednesday.

The movie made an extra $8m when it opened in 36 other countries including United Arab Emirates, Denmark, Germany, Russia and New Zealand.

King Kong was released in the UK on Thursday, a day after its North American launch.

US box office experts have blamed the films three-hour running time for its slow start.

But Universal said they were pleased with the opening and were upbeat about its long-term prospects.

"It's a great start, a great kickoff," said Universal Pictures distribution president Nikki Rocco.

"We know - based on the film's playability, reviews and feedback about word-of-mouth from exhibitors - that the film is going to be a huge success. In the tracking, the unaided awareness alone doubled in one day."

Based on the 1933 classic, the film follows a film crew's expedition to the unexplored Skull Island, where they encounter unfriendly locals, dinosaurs and a giant gorilla.

The movie stars Naomi Watts, Jack Back, Adrien Brody, Jamie Bell, Andy Serkis and Lobo Chan.

The first of Jackson's The Lord of the Rings films, The Fellowship of the Ring, opened in the US with $18.2m.

His second chapter, The Two Towers, debuted with $26.2m, while his final installment, The Return of the King, took $34.5m on its opening day.

Spider-Man 2 opened in the US with $40.4m, while Star Wars: Episode III Revenge of the Sith claimed the top opening day in US box office history with $50m.