Football Association chairman Greg Dyke has "serious concerns" about security ahead of the England v Wales Euro 2016 match on Thursday.

The two sides face off in Lens after England's previous Group B game against Russia was marred by violence on the streets of Marseille and inside the Stade Velodrome.

Six England fans have been jailed for their part in the fighting on the streets of the city in south France which involved 150 "hyper violent" Russian hooligans.

The men, aged from 20 to 41, all appeared at court on Monday and were given sentences of between one and three months.

Uefa threatened Russia and England with expulsion from the tournament following the ugly scenes.

Mr Dyke has written to the governing body of European football to defend the role of English fans in the crowd trouble during Saturday's match with Russia - and labelled the stewarding at the match "unacceptable".

In a letter in which he condemned the behaviour of certain England supporters on the streets of Marseille, he said: "The implication in your jointly-addressed letter is that English fans were in part responsible for the terrible incidents at the end of the match with Russia.

"This is contradicted both by the video evidence and by the fact your independent disciplinary bodies have only instigated sanctions against the Russian Football Union.

"We believe the stewarding arrangements in place were unacceptable. Supporters were able to get in with fireworks and flares, and then let them off, and there was insufficient segregation between the Russian and English fans, particularly given the events of the previous two days."

Referring to the match in Lens on Thursday, Mr Dyke said: "We are planning to use our high-profile individuals to ask English fans to act responsibly and in a respectful manner and we take seriously your suggestion of sanctions.

"We understand there is to be an alcohol ban across the host cities and we would welcome this, particularly in Lille on Wednesday where many English fans have been asked to gather ahead of Thursday's match against Wales in Lens.

"We have, following consultation with the authorities, advised our supporters without tickets for the match in Lens to congregate there, and whilst we will be working hard to positively influence their behaviour we have serious concerns around the security arrangements for the city in the next few days."