The final two games of the ban are suspended and will come into effect only if Inter fans are the cause of further trouble during a probationary period of three years, European soccer's ruling body UEFA said on Friday.

The Serie A club had feared expulsion from next season's Champions League given that this was a second offence.

In practice the ban means Inter will have to play without supporters for their next four UEFA competition home fixtures.

AC Milan were awarded the tie 5-0 on aggregate and will play PSV Eindhoven in the semifinals.

AC Milan won the first leg of the quarterfinal 2-0 and were leading Inter 1-0 when the game was stopped after 73 minutes when flares were thrown on to the San Siro pitch.

Inter are currently third in Serie A. If they finish in that position, or fourth place, they would enter the Champions League in the final qualifying round and play the home tie behind closed doors.

If they qualified for the group stage then all three of their home matches would be behind closed doors with fans only returning to the San Siro if Inter got through to the first knockout phase.

The continued presence of Inter supporters at the Milan venue would then depend on their good behaviour and the 'suspended' two-match ban would be in addition to any separate sanction for a further offence, UEFA said in a statement.

The ban would also apply to the UEFA Cup and would be transferred to the following season if Inter were eliminated before playing four games.

UEFA communications director William Gaillard denied Inter had escaped lightly.

He told BBC Radio Five: "There will be some people who think that it is lenient and other people who think that it is harsh.

"This is the highest fine in the history of UEFA and the loss of four home games will mean they lose out on revenue for around eight million euros (5.5million pounds).

"You have to put it in the context of the game. There were no further injuries apart from a very slight one to the goalkeeper which we absolutely regret anything in the last five years."

Internazionale president Giacinto Facchetti admits he is saddened by the penalties imposed by UEFA.

Facchetti told www.gazzetta.it: "We were hoping to have as few (banned) days as possible and now we will see what the reasons are.

"It is very sad to be playing behind closed doors and it will not be easy for the players to find the right atmosphere."

Facchetti claimed there was little the club could do to stop violence, saying: "From abroad, it's difficult to understand some things about Italian football -- certain incidents -- because they think control in the stadium depends on the clubs."

Inter earlier revealed they are to sue one of their fans who was arrested after the chaos at Tuesday night's game.

Fabio Roia, state prosecutor in Milan, revealed he has been instructed by the club's lawyers to begin proceedings.

"I think this is an important step," Roia said.

"It means that the club is distancing itself from this type of fan."

Roia said this is the first time a club has filed a suit in this kind of situation.

Tuesday's match was the second time this season that a Champions League game in Italy had been abandoned due to crowd trouble. AS Roma's tie with Dynamo Kiev was halted after Swedish referee Anders Frisk was hit by an object thrown from the crowd.

UEFA ordered Roma to play two games behind closed doors.