Police in Chicago, Illinois have launched an investigation into a video message posted online by a local gang which allegedly threatened the safety of rapper Rick Ross.

The hip-hop star was recently targeted by self-proclaimed members of a Chicago-based group known as the Gangster Disciples, who demanded Ross cut a cheque for their founder Larry Hoover if he wanted to press ahead with two performances in North Carolina last week (ends09Dec12).

Both gigs were subsequently scrapped - for no official reason - and rumours suggested the decision was linked to the gang's video threat.

Ross blamed promoters for cancelling the shows and vowed to return to North Carolina as soon as possible, but he subsequently pulled the rest of his U.S. Maybach Music Tour dates, insisting it was the result of an "apparent lack of organisation and communication" by event promoters.

Now detectives in Chicago have taken note of the gang's video clip and are looking into the YouTube.com post to find out if the threat was credible, according to Tmz.com.

Ross is no stranger to Hoover - he gives the former gang leader a shout-out on his 2010 song B.M.F. (Blowin' Money Fast). Hoover is serving six life sentences at a prison in Colorado for drug conspiracy and extortion convictions.