British Foreign Secretary Boris Johnson was in Moscow on Friday amid an acute strain in ties between Britain and Russia.

Johnson is the first UK foreign secretary to visit Russia in more than five years, reflecting tensions over Ukraine and other issues, Associated Press said in a report on Friday. 

Relations have also been strained by the 2006 poisoning death of ex-Russian spy Alexander Litvinenko.

Despite the differences, Johnson stressed the need for the two nations to cooperate on tackling international challenges, such as preserving the Iran nuclear deal and dealing with the crisis over North Korea.

"And when I look at the difficulties in our relationship, whether it's over Ukraine or over the Western Balkans, or what's going on in cyberspace, I agree with you that it's important to talk about these things and to be frank about them and to accept that they are obstructions in our relationship at the moment," he said. 

He said at the start of his talks with Russian Foreign Minister Sergey Lavrov that the two countries should "work together for peace and security".

"And as you say, we are both P-5 members, we both have a duty to our countries and to the world to work together for peace and security."