POLICE in Rossendale have issued a warning to parents after a group of more than 100 children were yesterday found swimming in an East Lancs reservoir.

This came as temperatures soared to around 30° on the hottest day of the year so far.

Police had previously warned against such dangerous behaviour at Clough Bottom and Calf Head reservoirs, near Haslingden.

A police spokesman said: "Today we have received numerous reports of large groups of youths swimming in our reservoirs with in excess of one hundred children being moved from the Grane Road area.

"Reservoirs can be extremely dangerous and we would ask parents to check on the whereabouts of their children today, if they are frequenting reservoir areas please advise them against this to prevent a potential tragedy."

Meanwhile residents have already expressed their dismay at swimming parties in the area.

A spokesman for the Grane Road Residents Association added: “We’ve seen parents with children and an inflatable dinghy.

“The gate has been pulled off its hinges so people can get in.”

Water companies have also warned of the danger.

Paula Steer, from United Utilities, added: “I would urge all parents to stress and stress again to young people, that no matter how inviting the water looks, it is deadly.”