Up to 3,000 Millwall fans have travelled to Hungary for the match

Two others, less seriously injured in clashes during the 3-1 defeat by Ferencvaros, have left hospital.

The Foreign Office said two of nine fans arrested during violence in the city centre were being held.

Millwall chairman Theo Paphitis has voiced concerns over security after visiting the fans in hospital.

Missiles thrown

He said: "I have serious concerns about a number of issues surrounding this tie, including the provocation our supporters were subjected to inside the ground.

"Missiles were being thrown at us, our players were subjected to racial abuse and there was a lack of security where it was needed.

"The Uefa delegate witnessed the situation and I will certainly be making my views known to Uefa," he said.

During the hospital visit, Mr Paphitis and chief executive Ken Brown, spoke to one of the fans, who had been transferred onto a ward. The other was still in intensive care.

Mr Paphitis said doctors expected both to return to the UK on Wednesday or Thursday and British Embassy staff would stay with them until then.

Up to 3,000 Millwall fans were in Hungary for the Uefa Cup first round second leg match, police said.

Black market tickets

In the most serious incident, in one of Budapest's main squares, rival supporters fought and shop windows were broken.

A witness said the police used teargas and mounted officers to end the clashes.

There were also reports of trouble inside the ground in the build-up to Middlesbrough's away game at Banik Ostrava in the Czech Republic.

Seats were ripped up and thrown by rival fans after Middlesbrough fans were able to buy black market tickets for the home end.

But the fighting was quelled by local police using batons and the game began on time.

Only 900 tickets were available for purchase by the Middlesbrough fans.

Fans without tickets had travelled to the Czech Republic and bought tickets from touts for as little as �5.