City manager Stuart Pearce revealed that Merseyside Police had informed him of an incident involving Barton immediately after the 1-1 draw at Goodison Park.

Barton, 23, is believed to have made the provocative gesture after Micah Richards' injury time goal cancelled out Andrew Johnson's first half strike.

The Everton supporters were enraged by Barton's actions and City goalkeeper Nicky Weaver had to lead him off the pitch after the final whistle.

Barton may now face an English Football Association investigation as well as the police probe and could be hit with a lengthy ban if found guilty.

Pearce said: "The police approached me afterwards to make me aware of what had happened.

"I did not see it. But if anything did happen, we will look at it with an open mind and deal with it.

"I am sure the timing of our goal had a lot to do with any over-celebration. Maybe also there was the fact that one or two people have been saying things about our away form."

It is not the first time Barton, who was on Everton's books as a schoolboy, has found himself involved in a controversial incident.

He was sent home from City's pre-season tour of Thailand in 2005 after becoming involved in a bar-room brawl.

And he was also hit with a club record fine for stubbing a cigar out in the eye of Jamie Tandy, a City youth team player, during the club's 2004 Christmas party.