'No Strings Attached' tops US box office

The week's only new film release No Strings Attached has topped the box office in its opening weekend.

The romantic comedy, which stars Natalie Portman and Ashton Kutcher, toppled last week's number one, taking $20.3 million.

Seth Rogen's superhero flick The Green Hornet falls to second place taking $18.1 million, followed by Vince Vaughn's comedy The Dilemma which took $9.7 million.

Colin Firth's critically acclaimed historical drama The King's Speech remains in fourth with $9.1 million, followed by the Coen Brothers' True Grit, which rounds out the top five with takings of $8 million.

Next week sees the release of a new horror in the form of Antony Hopkins's latest film The Rite, as well as the Jason Statham-led action remake of The Mechanic.

The US box office top ten in full:

1. (-) No Strings Attached - $20,300,000
2. (1) The Green Hornet - $18,100,000
3. (2) The Dilemma - $9,720,000
4. (4) The King's Speech - $9,100,000
5. (3) True Grit - $8,000,000
6. (5) Black Swan - $6,200,000
7. (9) The Fighter - $4,515,000
8. (6) Little Fockers - $4,390,000
9. (8) Yogi Bear - $4,060,000
10. (7) Tron: Legacy - $3,700,000