William Hague has said he wants closer economic and security ties with Russia despite unresolved differences over the murder of Alexander Litvinenko.
On his first trip to Russia as UK foreign secretary, Mr Hague said the killing of the former spy in London in 2006 remained a "big problem".
Russia has rejected an extradition request for the main suspect.
But Russian foreign minister Sergei Lavrov said the case should not be an obstacle to improved co-operation.
Relations between the two countries deteriorated markedly after the poisoning of Mr Litvinenko with the radioactive substance polonium-210 and have still not fully recovered.
UK investigators suspect former KGB agent Andrei Lugovoi of the murder and their 2007 request for his extradition to stand trial in the UK still stands.
BBC News
