Police in Northern Ireland have been left incredulous after a disgruntled woman called to complain her drug dealer had ripped her off by selling her sugar instead of cocaine.

The would-be drug user called the Craigavon police station after discovering she had bought what turned out to be brown sugar for £200 (NZ$360).

A post to the Police Service of Northern Ireland, Craigavon, Facebook page described the bizarre call as a warning to the public.

"Caller: I've been scammed.

Me: Ok, are you out any money?

Caller: Yeah I paid over £200 and got brown sugar instead.

Me: Instead of what?

Caller: Cocaine.

Me: Um..."