The first British man got into a dispute with a police officer on board the train and was detained. The second man hurt his hand but has been discharged from hospital, the source told Reuters.

Accounts of the incidents on Russian social media, which the source said were roughly correct, said the man detained had seized the service pistol of the police officer. The same post said the other injured man had cut his hand after breaking a window on the train.

Local police declined to comment and the Russian interior ministry was not immediately available for comment.

A British Embassy spokesman in Moscow said: “Our staff are in contact with the local authorities regarding a British man who was detained following an incident on a train in Russia. We stand ready to offer him assistance.”

England’s soccer team face Tunisia in their first World Cup match in Volgograd (formerly Stalingrad) in southern Russia.

Russian authorities have pledged to hold a safe and secure World Cup tournament, which is taking place in 11 cities and runs until July 15.

The Russian social media post, purporting to be a leaked internal railway operator’s report, said that the injured fan had broken a window on the train and received lacerations to his hand.

It said the other fan had grabbed the pistol of a police officer. The weapon was removed from the fan and he was detained.

The source with knowledge of the matter confirmed the outline of the incidents described in the post but gave no further details.

A duty police officer in a location where the train stopped en route to Volgograd said he heard such an incident had taken place but did not have details.

It was not immediately clear when the incidents on the train took place.