Keane was unhappy with the reaction from some fans during the 1-0 Champions League victory against Dynamo Kiev which was enough to send United into the second phase.

The Irishman told BBC Radio that some fans did not understand football and need to "get into the real world".

He said: "Sometimes you are going to have games like this but you just have to battle and that's what we did. At times the quality wasn't there, but hopefully that will come later on in the competition.

"We did feel in control of the match. Fair enough, we didn't create that many chances but they didn't either until the last minute of the match.

No understanding

"Our fans away from home are as good as any, but some of them come here and you have to wonder do they understand the game of football?

"We're 1-0 up, then there are one or two stray passes and they're getting on players' backs. It's just not on.

"At the end of the day they need to get behind the team. Away from home our fans are fantastic, I'd call them the hardcore fans.

"But at home they have a few drinks and probably the prawn sandwiches, and they don't realise what's going on out on the pitch," added Keane in a broadside at fans in the hospitality boxes.

"I don't think some of the people who come to Old Trafford can spell football, never mind understand it.

"To win games by three and four every time - these people need fantasy football. They need to get in the real world.

"We need to improve because it is definitely going to get harder. It's up to the players to pull their fingers out, especially away from home."

"I don't think we've reached anything like our peak yet and hopefully this first group phase will be a little bit of a kick up the backside for us.

"We've got to go on from here and produce better performances.

Last season, boss Sir Alex Ferguson asked for more noise from the crowd on European nights after admitting his disappointment at the lack of atmosphere at Old Trafford.