Three men have been arrested by counter-terrorism police on suspicion of spying on behalf of Russia.
The men, aged 48, 45, and 44, were arrested at addresses in west and central London on Thursday, Met Police said.
They were all arrested on suspicion of assisting the Russian intelligence service.
The men were detained under section 3 of the National Security Act and are now in police custody, the force added.
Officers are now carrying out searches of these addresses and another address in west London.
"We’re seeing an increasing number of who we would describe as 'proxies' being recruited by foreign intelligence services and these arrests are directly related to our ongoing to efforts to disrupt this type of activity,” Commander Dominic Murphy, Head of the Counter Terrorism Policing London said.
"Anyone who might be contacted by and tempted into carrying out criminal activity on behalf of a foreign state here in the UK should think again.
“This kind of activity will be investigated and anyone found to be involved can expect to be prosecuted and there are potentially very serious consequences for those who are convicted."
