The prime minister is under pressure to sack Conservative Party fundraiser Ben Elliot over his links to Russian oligarchs.
Labour has written to Boris Johnson, calling on him to sack the nephew of the Duchess of Cornwall, who raised nearly £2m from donors with links to the Kremlin.
He is co-founder of Quintessentially, a luxury concierge company that launched its Russia office in 2006 and has expanded it to roughly 50 employees at its base in Moscow.