US senators have asked President Bush to intervene on the side of William Browder, an activist hedge fund manager who has been barred from entering Russia since last year.

The request has come to light just as Sergei Ivanov, Russia's defence minister, warned other countries to stay out of Russia's affairs. Ivanov's comments were published in an article in the country's Izvestia newspaper two days before the start of a G8 summit in St Petersburg.