Cocklers have gathered to work at Lafan Sands, in north Wales

Groups of up to 90 cocklers have been working at Lafan Sands in north west Wales for the past 10 days.

Inspectors, who have been monitoring the situation closely, say they have not breached any fisheries regulations.

But conservationists are worried that sea birds' feeding grounds are being disturbed.

It is believed the cocklers have moved from Morecambe Bay after one bed was closed because of dwindling stocks.

The cockle bed is on the sands, which cover five miles of coast between Llanfairfechan and Penrhyn Castle.

Traeth Lafan is a site of special scientific interest and the cockle beds provide a food source for up to 4,000 oystercatchers alone.

Chris Wynne, conservation officer with North Wales Wildlife Trust said: "There's some concern about disturbance to birds. It provides massive feeding ground for waders, red shank and oystercatchers.

"The major concern is if large numbers of shellfish are removed, but there is also the worry over general disturbance - with people working and using vehicles and quad bikes on the beach."

The RSPB says it wants cockling controls to protect the oystercatcher population

The Royal Society for the Protection of Birds said most of the cockle beds in the area are relatively small and "we would not wish them to be over-exploited".

RSPB Wales conservation manager Tony Prater said: "It's difficult to control once teams of cockle pickers arrive."

The Countryside Council for Wales is gathering scientific evidence to establish if the birds are affected.

A spokesman said: "It's a public fishery site, cockling can be carried out provided they comply with the appropriate legislation.

"We are in discussion with the sea fisheries committee and the coastgaurd agency and have been on site to assess the situation."

Different organisations are responsible for different issues surrounding cockling and a meeting discussed the issue on Wednesday.

Jim Andrews, chief executive of the North Western and North Wales Sea Fisheries Committee, said they had statutory powers to ensure cockling was carried out properly, but there had been no evidence of dredging or the picking of cockles below the minimum size.

"We've had officers there over the last 10 days and I have three there again on Thursday and so far they have found no-one is doing anything wrong."

Cockling became more intensive in the north west of England at the end of 2002, with the issue coming to wider attention after the tragic drowning of 21 Chinese cocklers at Morecambe Bay in February this year.