Adam Osmayev, a Chechen fighter, was once accused of trying to kill President Putin

Ukraine’s security service says it has foiled a plot involving one of its own senior officers and Russia’s FSB spy agency to kill a Chechen who once allegedly planned to assassinate President Putin.

The Security Service of Ukraine (SBU) arrested Major-General Valery Shaytanov on suspicion of treason and planning terrorist attacks. He had acted as a go-between in a conspiracy to murder Adam Osmayev, 38, it said.

The arrest suggests Russia’s security services are continuing a campaign of killings in Ukraine despite signs of improved relations between Mr Putin and Ukraine’s President Zelensky.

Mr Osmayev, who was educated at a boarding school in the Cotswolds and studied economics at the University of Buckingham, was arrested in Odessa, Ukraine, in 2012 after two of his associates