Customs chiefs warned the public not to fall foul of cyber fraudsters posing as authorities in the Emirates to swindle large sums of cash.
The Federal Customs Authority (FCA) issued an alert after investigations uncovered plots being operated from both within and outside the Gulf region.
In a statement, the FCA said scammers purporting to represent them and other authorities in the country, using names and logos, were being closely monitored and legal action was being taken to shut down their practices.
The authority said fraud attempts included fake competitions on social media and emails promising prizes such as luxury cars, in exchange for fees of up to $5,000 (Dh18,364).
It urged members of the public who receive such messages not to respond to them and to immediately report them to the FCA.