LONDON (AP) _ Police said Monday they had arrested five people on suspicion of manslaughter over the deaths of 19 Chinese workers killed as they searched for shellfish in an English bay.

Lancashire Police said three men and two women were arrested Sunday and were being questioned about possible involvement in the deaths. They had not been charged and were not identified. Police did not say what role they were thought to have played in the deaths.

The workers, 17 men and two women, were killed by powerful tides Thursday in Morecambe Bay, a rich cockle-hunting area in northwest England known for its treacherous sands and tides. Sixteen survivors were rescued.

Police said some of the dead were recent immigrants living in crowded and often squalid conditions and employed at low wages by ``gangmasters.''

Collecting cockles _ a shellfish that lives just below the surface of muddy sand _ is estimated to be a multimillion dollar business in Britain, but is largely unregulated.

Geraldine Smith, the Labour Party lawmaker who represents Morecambe, called for cockle-picking to be licensed in the wake of the tragedy.

``We need better regulation of public fisheries, with perhaps a license of 500 before people can go cockle picking,'' she said. ``The money raised from these licenses could then pay for proper enforcement of safety at the bay.

``I also want to see licenses for all gangmasters. This would cut out the criminal element and stop the exploitation of workers.''

Detectives raided nine addresses in Liverpool, 40 miles south of the bay, over the weekend and seized computers, documents and equipment connected to Morecambe Bay cockle-collecting.

Detective Chief Inspector Mick Gradwell said police expected to stage more raids over the next few days.