Anti-Kremlin activist William Browder said Monday he had been blocked from flying to the United States after Russia placed him on an Interpol wanted list.

Browder, a Briton based in London, said the move was in retaliation for his support of Canada's passage last week of its "Sergei Magnitsky Law," which targets Russian officials for human rights violations and is named for a former employee of Browder who died in a Russian prison after exposing massive corruption.

"Putin adds me to Interpol wanted list in retaliation for passage of Canadian Magnitsky Act," he tweeted.

"Unless Interpol lifts this notice, I will be arrested at any international border I cross on Putin's orders," Browder added.

Browder, head hedge fund manager at Hermitage Capital Management, said that as a consequence his "Global Entry" membership for expedited immigration into the United States had been revoked and there were "problems" with his visa.

Browder said it was the fifth time Moscow had tried to place his name on an Interpol warning list.

This time was successful, he said, because they put him on a less rigorously vetted "diffusion notice" that can alert other countries of a wanted person's location or request the person's arrest.

A US official suggested this may have automatically sparked warnings in US immigration systems, leading airlines to prevent Browder from traveling.

But a spokeswoman for the US Customs and Border Protection agency said that Browder continues to be approved for entry into the country under the "ESTA" automatic visa waiver program.

"His ESTA was manually approved by CBP on October 18 -- clearing him for travel to the United States," she said.

Browder has led the global campaign for justice for Russian lawyer Sergei Magnitsky, who was jailed in 2008 after revealing massive fraud by Russian officials. Magnitsky spent 11 months in squalid prisons and died on November 16, 2009.

Pushed by Browder, in 2012 the US Congress passed the Magnitsky Act, which has allowed Washington to slap tough sanctions on more than 40 senior Russian officials, many with links to Putin, for their roles in the fraud Magnitsky exposed, its coverup, and his imprisonment.

The sanctions can block those named from visiting the United States, and lock them out of the US banking system, which can hinder their financial transactions around the world.

The Kremlin in particular has opposed the Magnitsky sanctions.

In June 2016, Russian lawyer Natalia Veselnitskaya offered officials of Donald Trump's presidential campaign negative information about his rival Hillary Clinton in order to gain a meeting with them to lobby for support to repeal the Magnitsky Act.

On Monday, The New York Times reported that Moscow prosecutors are now trying to build a case that Browder himself murdered Magnitsky.

Source: AFP