The huge security operation surrounding England's next Euro 2016 football match has been bolstered amid fears of a fresh wave of violence.
Extra British police will be deployed to France ahead of the next round of Group B matches and a uthorities in both England and Russia have appealed for supporters to behave in the wake of disorder in Marseille at the weekend.
French police have arrested 43 Russian fans suspected of being involved after stopping a bus in the Alpes-Maritimes region in the south of the country on Tuesday, according to local media reports.
And UK police are also assisting the investigation into the Marseille melee by scouring CCTV, social media and press images to identify any fans who were involved, the National Police Chiefs' Council (NPCC) said.
English fans suspected of disorder could face court action when they return to the UK in the form of football banning orders, the NPCC spokeswoman warned.
NPCC lead for football policing, Assistant Chief Constable Mark Roberts appealed for witnesses to send police any footage and said: "A number of images of those involved in disorder have been collated and work continues to identify those involved."
It comes after the first fan to appear in a UK court over the trouble in France was handed a five-year football ban, after a police "spotter" in the UK saw video of the man "throwing a chair".
Mea nwhile, Uefa have handed Russia a suspended disqualification from the tournament following the crowd disturbances at the game against the Three Lions in Marseille on Saturday.
The Football Association were previously warned that further disorder could lead to the England team also being kicked out .
But concerns have been raised about the security of fans as England prepare to take on Wales in Lens on Thursday and Russia play Slovakia in Lille on Wednesday, with the northern French cities just 23 miles apart.
The security operation in Lens, which one local official said would be "in lockdown", will be boosted by additional British police officers and also by British Transport Police, who will extend patrols from Eurostar trains to local rail services.
Fabienne Buccio, prefect of the Pas-de-Calais region, said 1,200 police officers and 1,200 private security workers would be on duty on the day of the game.
A ban on off-licences selling alcohol will also be in force in both cities between Tuesday evening and Friday morning.
Answering an urgent question in the Commons on Tuesday, Theresa May said British police officers known as "spotters" who are trained to identify troublemakers have been sent to France.
The Home Secretary told the chamber: "And in fact whatever the French have asked for then we are willing to provide to them, and as I said, that goes both for police and British Transport Police."
She said that for "operational reasons" she would not reveal how many officers are being sent across the Channel.
A NPCC spokeswoman said the additional officers being deployed for the England game against Wales had "already been agreed with the French" prior to the tournament, rather than a "reaction to what's happened recently".
And BTP Assistant Chief Constable Alun Thomas said: "In addition to the patrols on Eurostar trains, officers will now extend their patrols on French rail services in order to support fans.
"Working with the French authorities, we will continue to monitor the situation and send officers where they are needed."
Some 50,000 English and Welsh supporters are due to descend on Lens, while many fans are also expected to be staying in Lille and Mrs May said the Foreign Office is advising England fans without tickets not to travel to either city.
Six British fans were jailed for between one and three months on Monday for their part in the Marseille violence, while on Tuesday 24-year-old Birmingham City supporter Daniel Warlow was given a five-year football banning order for his part in the disorder on Friday, June 10.
Earlier, FA chairman Greg Dyke said he has "serious concerns" about the security of fans, while Russia manager Leonid Slutsky asked his nation's supporters to display "correct behaviour".
A group of 150 Russian hooligans, known as ultras, who were involved in the Marseille trouble and were described by French authorities as "hyper violent" and "hyper rapid" are also feared to be still at large.
There has already been talk on social media of some England fans seeking revenge on their Russian counterparts, with one user on Twitter suggesting the "English cavalry is comin", and looking for a "tear up" in Lens on Wednesday.
Another tweet said: "You don't press on the English without expecting some fight back. We can take the fight to their level" after boasting of a fight with four Russians while travelling through France following Saturday's game.
Meanwhile, a group of Russia supporters simply posted "R.I.P english hooliganism".
Source: PA
