BOGUS collectors, who say they are working on behalf of Weston Park cancer hospital, have been preying on people in Barnsley.
A group claiming to be raising money for the hospital's charity have visited houses in the town centre asking for donations.
But the charity does not currently use canvassing to raise money and a spokesman warned people to be vigilant.
The matter has been reported to the police, which is investigating.
Contact the charity office on 0114 2265751.