Amanda Seyfried's new movie Dear John has bumped Avatar off the top of the US box office.

The romance - which centres on a long-distance love story between a soldier (Channing Tatum) and his sweetheart (Seyfried) back home - debuted at No 1 with 32.4 million dollars.

It knocked off James Cameron's sci-fi epic after seven weekends in first place, according to studio estimates on Sunday.

"It is very cool to know that it was our movie that audiences just totally embraced and made No. 1 for the weekend," said Rory Bruer, head of distribution at Sony. As for runaway blockbuster Avatar, he quipped: "I think they're going to be fine in the long run."

Avatar slipped to No 2 with 23.6 million dollars, raising its total in America to 630.1 million.

The film has now taken a record 2.2 billion dollars worldwide, surpassing Titanic, which was also directed by Cameron, which took in 1.8 billion globally.

Avatar had been No 1 in the US longer than any movie since 1997's Titanic, which held on to first place for 15 weekends.

In third place at the box office was spy story From Paris With Love - starring John Travolta and Jonathan Rhys Meyers as CIA men trying to crack a terrorist plot - which took 8.1 million dollars.

Estimated ticket sales for Friday to Sunday at US and Canadian theatres are according to Hollywood.com. Final figures will be released on Monday.