US companies returning to Russia risk having their businesses and staff “robbed and killed”, campaigners have warned, amid calls from the Trump administration to rebuild economic links.

Sir Bill Browder, a financier turned anti-Russian corruption campaigner, said American businesses should be wary of the risks of returning to the country.

Sir Bill, whose fund was once Russia’s biggest foreign investor, said: “American companies will do what’s in their self interest, and there’s no self interest in going into Russia where you can be robbed and killed. Nobody is going to risk their capital.”

Sergei Magnitsky, a lawyer who represented Sir Bill in Russia, was tortured and killed in a Moscow prison in 2009 after he uncovered a web of alleged corruption. Sir Bill has since been on a mission to secure justice for the Magnitsky family. In 2012, the Magnitsky Act was passed in the US to punish those who could have been involved in his death.

His comments come after Marco Rubio, the US secretary of state, claimed there were “incredible opportunities that exist to partner with the Russians, geopolitically on issues of common interest and frankly economically”.

Closer economic ties between the US and Russia were discussed at a meeting between the two countries in Saudi Arabia this week, which principally focused on how to end the war in Ukraine. The summit has provoked panic and outrage in Kyiv and other European capitals for excluding the Ukrainians and European leaders.