Wigan Athletic have sacked Marlon King after the striker was sent to prison for 18 months today for groping a woman and breaking her nose after she rejected his advances in a nightclub.

The 29-year-old was convicted of sexual assault and causing actual bodily harm by a jury at Southwark Crown Court in London.

“We have to follow the rules and regulations, which means we will have to give him 40 days notice that his contract will be cancelled," Dave Whelan, the Wigan chairman, said. "He is absolutely sacked - we will not tolerate football players who get sent to jail for 18 months. As far as we are concerned, he is finished with football at Wigan Athletic.”

The court was told how King, celebrating his wife's pregnancy and scoring a winning goal hours earlier, was repeatedly cold-shouldered by women in the Soho Revue Bar in London last December. When one university student rejected his advances, the court heard that King told her: "I'm just out of your league, I'm a millionaire. She replied: "I don't care who you are, take your multi-millions and get away from our table."

The prosecution then said that King lashed out in fury and knocked her to the floor with a single clenched-fist blow so powerful that two other revellers were sent flying.

“You have shown not a hint of shame at your disgraceful and arrogant behaviour,” Judge Nicholas Loraine-Smith told King yesterday.

King, from Waltham Cross, Hertfordshire, insisted he was the victim of mistaken identity. But a number of witnesses convinced the jury he was lying, and King was convicted of sexual assault and actual bodily harm by a jury by a margin of 10-2. He showed no reaction. He will now have to register as a sex offender for seven years, pay £3,125 compensation to his victim and £1,800 prosecution costs.

As the sentence was pronounced, several of King’s supporters swore at the judge and loudly accused him of “institutional racism”. One, referring to the acquittal of the Liverpool captain for affray, shouted: “Steven Gerrard’s still walking the streets.” Another added: “Heil Hitler.”

King began his career at Barnet. In 2002, when a rising star at Gillingham, King served nine months of an eighteen-month sentence for handling stolen goods. He was caught at the wheel of a stolen BMW convertible and told police that it had been his for two months, but it had been stolen from outside a house in Chelsea four weeeks earlier and fitted with false number plates.

King also has previous convictions for wounding, theft, fraudulently using a vehicle excise licence and driving offences and he also had a community rehabilitation order imposed for attempting to purchase a laptop with a cloned credit card and damaging property as he was detained by store security staff. He has been acquitted of another charge of smashing a bottle over a policeman's head.

King returned to Gillingham after his release and was sold to Nottingham Forest in 2003 for £950,000, moving on to Watford in 2005, where he had a prolific goalscoring record. He joined Wigan in January, 2008, for £5 million, but struggled to break into the side and went on loan to Middlesbrough and Hull City last season. He is a Jamaica international.

In November, 2008, when at Hull, he was allegedly involved in a fracas with Dean Windass in a casino in Scarborough. Hull said that that the matter had been dealt with internally. The following month, only a few days before the Soho bar incident, King was banned from driving for 56 days after being caught speeding at 106 miles per hour on a stretch of road with a speed limit of 60mph.

He becomes the highest-profile footballer to be sent to prison in Britain since Joey Barton, the Newcastle United midfielder, who was jailed for six months in May last year for beating a teenager in the street.