04/09/2011 14:46 BST | Updated 04/11/2011 05:12 GMT

Swimmers Missing Off Dorset Coast - Search Underway

Four people remain unaccounted for following a sponsored swim off the Dorset coast.

Participants had been swimming in the sea between Bournemouth and Boscombe's piers to raise money for the British Heart Foundation.

At one stage, up to nine people had been reported missing. However, a number of them were later confirmed to have gone home without informing event organisers. It is unclear whether the remaining four have done the same, coastguards are still carrying out searches.

Organisers raised the alarm shortly after 2pm after a head count showed people were missing.

It resulted in three lifeboats and the coastguard helicopter being deployed.

Organisers said no luggage had been left at the race start, suggesting those unaccounted for "may have just gone home".

Coastguards are continuing the search and are urging the swimmers, if they are safe, to get in touch so the search can be called off.

An estimated 1,000 people take part in the annual 1.4 mile Pier to Pier charity swim.

Participants, who register prior to the event, wear red or yellow coloured swim hats and wristbands. The swimmers were divided into two events - the first, at 10am, was scheduled to finish at midday.

The second, which started at midday was expected to end at 2pm.