The investigators from the UK's Department for Work & Pensions say they receive more allegations of benefit fraud concerning Britons in Spain than in any other country where British people live.
The department is now planning a crackdown on these benefit cheats, the British Embassy in Spain said in a statement on Monday.
Launching the campaign, David Freud, Minister for Welfare Reform, said: "Taxpayers’ money should be going to the people who need it most, not lining the pockets of criminals. The vast majority of British people overseas are law abiding. But those who are fraudulently claiming benefits while living abroad are committing a crime. We are determined to put a stop to it."
In the campaign, investigators will be taking aim at the three most common types of benefit fraud in Spain.
These include people who are on means-tested benefits going abroad but who fail to declare their absence, and people who have undeclared property abroad.
The third group comprises people who are working while claiming sickness benefits.
Investigators also said claims for Income Support or Pension Credit are the most frequently investigated for fraud in Spain..
Anyone wanting more information can call the free and confidential fraud hotline on 900 554 440, or fill in the online form available at www.dwp.gov.uk/benefit-thieves-spain.