Part premiere, part Trump protest, Londoners gather for Oscar movie

Thousands of people braved London's winter drizzle on Sunday for a screening of the Oscar-nominated movie that has become a rallying point for opponents of U.S. President Donald Trump’s immigration policy.

Hours ahead of what looked set to be the most politicised Academy Awards for years, London Mayor Sadiq Khan made clear his political motivation in hosting the British premiere of the "The Salesman", whose Iranian director is boycotting the Hollywood ceremony.

"President Trump cannot silence me," Khan said to cheers from the crowd gathered in Trafalgar Square. "We stand in solidarity with Asghar Farhadi, one of the world’s greatest directors."

Farhadi, who won an Oscar in 2012 for "A Separation", is bookmakers’ favourite to win another Best Foreign Language Film statuette later on Sunday but is staying away in protest at Trump’s attempt to ban people from seven Muslim-majority countries from entering the United States.

In a video message from Tehran, Farhadi thanked the "dear people of London who are gathered on this cold afternoon", and said he was heartened by the reaction of filmmakers and artists to "the oppressive travel ban of immigrants".

"I hope this movement will continue and spread for it has within itself the power to stand up to fascism, be victorious in the face of extremism and saying no to oppressive political powers everywhere," Farhadi said.

The directors of the four films he is up against – from Sweden, Germany, Denmark and Australia – joined Farhadi in issuing a joint statement ahead of the Oscars criticising a "climate of fanaticism and nationalism" in the United States and elsewhere.

Mike Leigh, the many-times Oscar-nominated British director, hailed Farhadi as "the master" for filmmakers like him "who make films about real people and issues".

"Our protest is of course against Donald Trump’s cynical, divisive and destructive policies, especially his unforgivable travel ban," Leigh told the London crowd.

Khan's decision to host the movie event once again put him at odds with the British government which has been quick to forge close relations with Trump, particularly as Britain prepares to leave the European Union.

On his election as mayor last year, Khan, a Muslim who is one of the most prominent figures in the opposition Labour Party, said Trump had an "ignorant" view of Islam. He has since called on the government to rescind its invitation for Trump to make a state visit to London.