Celtic midfielder Stuart Armstrong said the Hoops had been left "feeling hard done by" after a late goal condemned them to a 1-0 defeat to Inter Milan and ended their Europa League campaign.

Ronny Deila's side played more than half the match with 10 men after the 36th-minute dismissal of Virgil van Dijk, but held out until the 88th minute before a fine strike from Fredy Guarin settled the tie 4-3 on aggregate.

"Disappointing is the word," Armstrong said. "We put a lot into the game but unfortunately we got nothing out of it."

Celtic were unhappy with Van Dijk's red card, and were still arguing with the referee after the final whistle.

"I think we all saw it as a bit harsh," Armstrong said. "The two yellow cards are not merited but it was what it was and it was an uphill battle from there. We just had to get on with it.

"We still created chances and probably should have tucked one away but of course the sending-off changed the game and we were on the back foot from there."

Van Dijk's red card was not the only decision to go against the Hoops on the night, with Armstrong tumbling under a challenge from Davide Santon only for the referee to wave away their penalty appeals.

Asked if he was fouled, Armstrong said: "Of course, if there wasn't (contact) I would have gone on and taken the shot. There's no need to go down but I felt an arm on my shoulder and it put me off balance.

"It's just the way it's gone for us unfortunately. There's a lot of disappointed boys in there feeling hard done by but it's done now."