The constant star: Weisz beats rivals to prove she is best of British

She has proved blockbuster fare in The Mummy and a London Film Festival glamour girl in that stunning Roland Mouret dress.

But now Rachel Weisz is finally winning critical plaudits for her movies, too. At last night's British Independent Film Awards 2005, the only prizes dedicated to independent British films, the 34-year-old scooped the best actress honour for her performance in The Constant Gardener, against rivals Dame Judi Dench, Natasha Richardson and Joan Allen.

It was a night of triumph for the John Le Carré adaptation, whose other star, Ralph Fiennes, has been tipped for an Oscar. The political thriller about a suspect pharmaceutical company in Africa was named best independent film against competition including Stephen Frears' Mrs Henderson Presents and The Libertine, starring Johnny Depp. Fiennes won best actor - in a shortlist that included Depp and Bob Hoskins - for his role as a timid diplomat left to piece together events surrounding the murder of his wife, played by Weisz.

Elliot Grove, who founded the awards eight years ago, said: "They are outstanding performances. I think that both Fiennes and Weisz could justifiably be expected to be tipped for Oscars."

The ceremony, hosted by James Nesbitt at the Hammersmith Palais in London, also saw success for The Descent, a horror movie about cavers trapped by a rockfall. Its 35-year-old director, Neil Marshall, beat competition from the veterans Michael Winterbottom and Stephen Frears, as well as The Constant Gardener's Fernando Meirelles, to be named best director. The film also took the best technical achievement prize for its editor, Jon Harris. Another horror movie, Evil Aliens, won the Raindance award for new talent.

The Richard Harris award for outstanding achievement was presented to Tilda Swinton at the end of a year in which she was virtually unrecognisable in Jim Jarmusch's Broken Flowers. She is about to be unveiled as the White Witch baddie in The Chronicles of Narnia: The Lion, The Witch and The Wardrobe.

Mr Grove said she epitomised the spirit of British independent film-making. "She is an extremely principled and pure artist and not above going to scoop up a nice big cheque from Hollywood. She is a wonderful artist," he said.

Keira Knightley collected the Variety UK personality of the year award after the producers of the sequel to Pirates of the Caribbean rearranged filming so she could attend. Mr Grove said: "She's young, she's talented, she's female and she's had all these successes." Rosamund Pike took the honours for her role in The Libertine in the best supporting actor/actress category, against a list including Bill Nighy for The Constant Gardener and her Libertine co-star Tom Hollander.

The jury, which included Alan Cumming, Amanda Donohoe and Hugh Hudson, named the New Zealander Emily Barclay, 19, as the most promising newcomer for her performance in In My Father's Den, a UK/New Zealand co-production. Her rivals curiously included the Coronation Street veteran Thelma Barlow for her big-screen debut in Mrs Henderson Presents.

Frank Cottrell Boyce, a frequent collaborator with Michael Winterbottom, took the best screenplay prize for Millions, which was also turned into an acclaimed children's book. Festival, Annie Griffin's comedy of life at the Edinburgh Festival, won her the debut director's prize and Gypo!, a low-budget film starring Paul McGann, won the best achievement in production prize.

Mr Grove said all the nominations were exactly what one might expect from Britain, "where film-making is edgy, exciting, entertaining, acultural... I think it's a pretty good list and a list that any country in the world would be proud to call its own."

The winners

* Best British independent film: The Constant Gardener

Best actor: Ralph Fiennes, The Constant Gardener

Best actress: Rachel Weisz, The Constant Gardener

Best supporting actor/actress: Rosamund Pike, The Libertine

Most promising newcomer: Emily Barclay, In My Father's Den

Best director (sponsored by The Creative Partnership): Neil Marshall, The Descent

Best screenplay (sponsored by BBC Films): Frank Cottrell Boyce, Millions

Douglas Hickox Award (debut director) (sponsored by Cineworld): Annie Griffin, Festival

Best technical achievement: Jon Harris, editing, The Descent

Best achievement in production (sponsored by Recorded Picture Company): Gypo!

Best foreign film: Downfall

Best documentary (sponsored by Bloomberg): Liberace of Baghdad

The Raindance award: Evil Aliens

Richard Harris award: Tilda Swinton

Variety UK personality of the year award: Keira Knightley