Racist abuse on social media shows no sign of diminishing in European football after British police launched an investigation into abusive tweets sent to Liverpool striker Mario Balotelli.

The Italian international tweeted "Man Utd...LOL" on Sunday after Liverpool's rivals Mancheser United slumped to a surprise 5-3 defeat by Leicester City in the English Premier League, seemingly provoking a discriminatory response.

"We can confirm officers are looking into offensive comments made on Twitter about Mario Balotelli," said Merseyside Police on their official Twitter feed.

The 24-year-old Balotelli's tweet was retweeted 150,000 times and was met with a torrent of abuse.

"We extend our support to Mario Balotelli after the appalling racist abuse directed at him on Twitter," said British anti-racism group Kick It Out.

"A large number of social media users alerted us to the messages by tweeting our official account and we have since reported this via True Vision -- the police's online reporting facility.

"During the 2013/14 season, 50% of all complaints submitted to us from across the game related to social media abuse," added the Kick It Out statement.

"The issue has been escalating and we urge fellow social media users to assist in bringing this type of abuse to the attention of the authorities by reporting directly to True Vision."

In an interview with CNN in 2013, Mario Balotelli -- then an AC Milan player-- vowed to walk off the pitch if he was racially abused at a football game.

That was after he was subjected to racist chanting during an Italian league game against Roma at AC Milan's San Siro stadium.

The 22-year-old put his fingers to his lips in front of the visiting supporters' section as a section of fans directed "monkey chants" at him and then teammate Kevin Prince-Boateng.

In August, Balotelli joined LIverpool from Milan in a $26.5 million deal.

The Italian has scored one goal since signing -- in Liverpool's 2-1 Champions League win against Ludogorets -- but the Merseyside club has had an uncertain start to the domestic season, losing three of their opening five games.

The Italian is well known to English football fans after a turbulent two-and-a-half-year stint with Manchester City, where he helped the team to a first league title in 44 years while also gaining a cult following for his off-field antics.

(CNN)