England soccer manager Gareth Southgate says he and his team are not being distracted from their preparations for the World Cup in Russia by the tensions between London and Moscow.

On Wednesday, the British government said it would kick out 23 Russian diplomats, the biggest such expulsion since the Cold War, over a chemical attack on a former Russian double agent in England that Prime Minister Theresa May blamed on Moscow.

May said no British ministers or members of the British royal family would attend the World Cup, which Russia is hosting in June and July.

Some politicians have called for a full boycott of the event, but Southgate said he was concentrating on his job.

"As far as all my briefings and information is, we're preparing to go to the World Cup, there's no doubt in our mind that's what we should be doing," Southgate told a news conference.

"Clearly it's a really serious matter and it's developing very quickly. But my job as the England football manager is to concentrate on the football and prepare the team.

"And the only thing at this stage that is of highest importance is the safety and security of our players and absolutely of our travelling supporters. They're the things we're focused on really," he said.

England begin their tournament on June 18 when they face Tunisia in Volgograd.