A leading public school has defended its actions in taking students out on Morecambe Bay's lethal sands in the wake of last week's cockling tragedy.

Coastguards went to Silverdale after receiving a 999 call from a resident alarmed at seeing 14 Sedbergh School students jumping up and down on the notorious mudflats and walking seawards.

Liverpool Coastguard Carl Hilton said the service should have been advised of the trip coming so soon after 19 Chinese cocklers were swept to their deaths.

"Everyone is particularly sensitive and concerned about the sands at the moment, and it is not surprising we were alerted. It would be helpful to be told in advance if anyone planned to do anything in Morecambe Bay at the moment.

"Although the students were in no immediate danger, a resident was very alarmed at seeing them walking seawards. We gave the group advice on safety."

A spokesman at the school, who refused to be named, confirmed a party of A level geology students, and a member of staff, had been taking part in a field trip to look at land formation.

He said they had been jumping on the sands to "create certain responses" from sand and water. "It might have looked bad to the naked eye, but really it was not."

He agreed the timing of the trip "was probably unfortunate", but added the experiments were needed for A level course work.

"What we were doing was very different to a cockling expedition by people unfamiliar with the area. It was a controlled experiment by a very experienced member of staff."

Sedbergh School later issued a statement apologising for any alarm caused. It said the group was restricted to a maximum shoreline distance of 100m.

"No channels were crossed and the area studied did not have quicksands, with normal public access. This is a routine component of A level study and the site has been visited for 20 years."

The school stressed the visit had been planned for many months and had been subject to thorough risk assessment.