The object hit Frisk on the forehead as he was walking towards the tunnel at half-time and blood poured down his face as he was helped to the dressing room. Dynamo were leading 1-0 at half-time at the Olympic stadium.

The first-half had ended controversially with Roma captain Francesco Totti booked and French defender Philippe Mexes sent off for lashing out at Maris Verpakovskis, which provoked an angry reaction from the home supporters.

Frisk received medical attention in a corridor and was later driven to hospital after being struck by what is believed to have been a cigarette lighter or a coin.

The second-half was delayed for nearly an hour before it was decided to suspend the match. The decision to call off the tie was taken by Frisk himself.

UEFA delegate Andre Francioli explained: "Frisk suspended the match because of the seriousness of his injury. He was not well enough and he was worried about his safety.

Asked what punishment might be handed out to Roma, Francioli replied: "UEFA's disciplinary commision will decide what happens."

The ugly incident is likely to land Roma in hot water.

The Serie A club will inevitably be fined and Kiev could be awarded the three points.

Roma, a club that has a poor disciplinary record, may also be forced to play their remaining first phase matches at a neutral stadium.

Fans of the club have a history of violence. Last season they forced the Rome derby against Lazio to be abandoned after a rumour spread around the stadium that a young Roma fan had been run over by a police van.

The rumour, which turned out to be false, sparked serious crowd disorder which left 150 police officers injured.

In addition to a hefty fine, Roma received a three-match stadium ban and had to play their home matches in the Sicilian city of Palermo.

Mayor of Rome Walter Veltroni was appalled by Wednesday's violence.

"What happened at the Olympic stadium was a disgrace," he said.

"It comes just a few months after those incredible scenes at the Rome derby last season that were offensive for the sport and damaging for city.

"It doesn't matter whether or not the referee makes a mistake - nothing can justify this act of violence. Any reasonable person would find it unacceptable."

There were also ugly scenes in Rome two years ago after a Champions League match against Turkish side Galatasaray, but on that occasion the fans were not to blame.

Fighting involving players and officials broke out after a bad-tempered 1-1 draw and riot police had to seperate the two sides.