Immigration officials have launched their largest ever crackdown on people working illegally as cockle pickers.
Cockling can be a lucrative business
More than 200 officials and police swooped on cockle beds on the River Dee in Wirral, Merseyside, where workers reportedly earned up to £1,200 a day.
Operation Omega, which began on Wednesday, was led by the Department for Work and Pensions (DWP) and was mainly targeted at benefit cheats and asylum seekers.
The DWP later confirmed 383 people were interviewed and 66 of them were found to be claiming benefits while working.
Half withdrew their benefits claims and the others are subject to further investigations.
The Immigration Service was unavailable to comment, but reports suggested no suspected illegal immigrants were arrested.
A ten-tonne lorry was impounded and 47 cars were found to be untaxed.
It follows a similar operation in Morecambe, Lancashire, on Monday, in which 37 suspected Chinese illegal immigrants were detained.
In total, about 800 cockle pickers work the beds at Thurstaston, Wirral.
Roy Paul, DWP Regional Fraud Operations Manager, said benefit fraud in the North West alone cost £88m a year.
"We are determined to clamp down on this type of fraud and will keep coming back until we do so," he said.
"We're responding to intelligence reports we've been gathering for the last five to six weeks following a similar operation we did in Morecambe Bay.
"That operation told us that up to a third of the cocklers were on benefit and not reporting their true circumstances to the department, so we are here to interview them, find out their identity details and make sure their benefits are correct.
"We've been told that between £500 and £1,200 a day is the going rate for cockling which is far in excess of their benefit entitlements."
Cockles picked in the Dee estuary are either transported by boat to Spain and Belgium or taken by road to other parts of Europe.