The British Prime Minister has made an embarrassing mistake on Twitter.

David Cameron's used the site to comment about the roll out of a cap on benefits.

But his tweet also referred to a spoof account of Work and Pensions Secretary, Iain Duncan-Smith.

The spoof account contains posts such as "I've always supported a Mansion Tax. Your Tax buys my Mansion. Chin chin!"

We're rolling out a cap on Benefits today - @IDS_MP and I are determined to make work pay, and help the UK compete on the #GlobalRace.

— David Cameron (@David_Cameron) July 15, 2013