LOS ANGELES (Reuters) - Horror sequel "Resident Evil: Retribution" grabbed the top spot at the U.S. and Canadian box office over the weekend with $21.1 million, studio estimates released on Sunday showed.

A 3D version of Walt Disney Co cartoon "Finding Nemo" took the No. 2 spot in the U.S. and Canadian box-office charts with $17.5 million, Disney said.

Demon flick "The Possession" slipped to third place after two weeks at No. 1, ringing up sales of $5.8 million.

"Resident Evil: Retribution" is the fifth movie in a franchise that stars Milla Jovovich as heroine Alice in a battle against the Umbrella Corporation and its army of zombies.

Domestic sales were in line with distributor Sony's pre-weekend projection for the low- to mid-$20 million range.

In international markets, the film added $50 million, for a worldwide total of $71.1 million. It did particularly well in Asia.

Sony president of distribution Rory Bruer credited Jovovich for the continuing success of the "Resident Evil" franchise.

"Every country she goes, they (audiences) fall in love with her," he said. "The 3D and Imax elements complement the franchise in a certain way, but the big money is on Milla."

The studio spent $65 million to produce the sequel. The four earlier films amassed global ticket sales of more than $660 million since the first movie in 2002.

Asked whether audiences should anticipate another "Resident Evil" installment, Bruer said: "I would count on it."

Meanwhile, families headed to theaters to see "Finding Nemo" for the first time in the 3D format. The movie ranks as one of the most successful from Disney's Pixar animation studio, generating global sales of $868 million during its original run. It won the Academy Award for best animated feature.

Disney spent less than $5 million to convert the film to the 3D format. Although weekend numbers came in slightly lower than Disney's original projections, Disney's executive vice president for motion picture distribution Dave Hollis said the tally was in line with previous 3D re-release openings.

"It's great for families during the day, and then couples at night," Hollis said, noting the fairly balanced age and gender spread of the weekend audience.

The movie is one of a handful of films Disney is bringing back to theaters in 3D after last year's success of "The Lion King 3D", which grabbed $94 million.

Rounding out the top of the charts, Prohibition-era drama "Lawless" earned $4.2 million during its third weekend in theaters to land in fourth place. Animated kids movie "Paranorman" finished in the No. 5 slot with $3 million.

Sony Corp's movie studio released "Resident Evil". Lions Gate Entertainment distributed "The Possession". The privately held Weinstein Co released "Lawless".