Paris, Jun 7 (IANS): Three crew members of the National Society of Sea Rescue (SNSM) were killed on Friday after their boat capsized near the seaside town of le Sables de L'Olonne in western France amid strong winds.

They were part of a crew of seven who were dispatched on a rescue boat to provide assistance to a fishing trawler which had launched an alert earlier on Friday, SNSM President Xavier de la Gorge was cited as saying by Xinhua news agency.

"Three rescuers died. This is a tragedy and a great shock to us," Yannick Moreau, Sables de L'Olonne Mayor, told BFMTV news channel.

"We do not know the circumstances in which the fishing boat had sailed and triggered the alarm which caused the SNSM intervention. We are still searching for the disappeared boat," Moreau said.

The report added the four other rescuers swam back to the shore.

The national weather centre Meteo France warned that strong winds will lash many areas in western France, placing 10 departments on orange alert, the second highest alert on the agency's scale, and urged residents to be vigilant.

Winds are expected to reach up to 120km/hr in these zones where large waves were feared.