Fresh questions have been raised over the conduct of Rangers fans after last night's Champions League game involving the Glasgow club in Romania erupted in violence.

Trouble flared outside the ground in Bucharest ahead of the game against Unirea Urziceni and there were further ugly scenes inside the stadium at half-time when fans ripped up seats and fought with stewards. Rangers fans were targeted by police with CS spray before kick-off when they complained that they could not get into the ground because too few turnstiles were open.

It is just 18 months since the Uefa Cup final in Manchester was marred by rioting Rangers fans. Supporters went on the rampage after an outdoor screen showing the match broke down just before kick-off, culminating in violent clashes with police.

Martin Bain, chief executive of Rangers, said he did not "condone" the appalling behaviour of some fans in Bucharest, but claimed that poor entry access at the Steaua Stadium and over-zealous policing had contributed to the problems. He is to lodge an official complaint with Uefa, European football's governing body, over the handling of the match by the local authorities.

"Obviously the behaviour of some of the fans inside the stadium was unacceptable and no-one likes to see that," Bain said. "However, what was equally unacceptable was the fact that Rangers came to this stadium with representatives from Uefa and Unirea a number of weeks ago and arranged for the four turnstiles to be open to give access to our supporters.

"When they arrived this evening there were only two turnstiles open which caused difficulty gaining access and [for] fans then to be sprayed with CS gas is totally unacceptable.

"I will now make representation to Uefa in their behalf."

Mayhem broke out when a mob of about 60 away supporters attacked staff at the Steaua Stadium. The chaotic scenes were captured on Sky Sports, with fans ripping up seats from the stand and throwing them at stewards.

Andy Kerr, president of the Rangers Supporters Assembly, described the trouble as a "minor incident".

"There was a bit of pressure at the front," Kerr said. "Spray was used, which was used before the start of the match, and I think people reacted to that.

"I wouldn't say the Rangers fans did anything wrong. The organisation was very poor."

Mr Kerr said he did not see any fans ripping up seats, but stressed such behaviour was unacceptable. "We don't condone it, we don't want to see it, but the vast majority of people behaved impeccably," he added. "In the big scheme of things, [it's] a minor incident."

Uefa said it will wait on a delegate’s report, due to be handed to the organisation later today before launching an inquiry into the trouble and deciding whether action should be taken against the club. Rangers have previously been fined by Uefa for the conduct of their fans.

"As far as we can establish at the moment, it seems there were a number of Rangers supporters who came late into the stadium and we need to find out why," Rob Faulkner, a spokesman for Uefa, said.

"Then there was an issue about where they were going to sit as apparently there were banners already placed there, which resulted in the request to remove some banners, which seems to have ended in a clash between stewards and some supporters.

"If we need to discuss with people who were there on site we will do that, and obviously we'll take action after that. In the next couple of days we should know."

The match, played at the ground of Steaua Bucharest, ended in a 1-1 draw.