IN a tiny, candle-lit chapel, heartbroken schoolchildren tried to find comfort in their darkest hour yesterday.

The day after losing their friend, Daniel Readshaw, in a tragic swimming pool accident, pupils at St John's RC School, in Bishop Auckland, County Durham, gathered for a special Mass in his memory.

Daniel, 13, died two years after his sister, Anne-Marie, also 13, died in almost identical circumstances.

Staff had offered the 1,200 students the chance to stay at home, but more than 120 chose to share their grief with their equally devastated teachers.

As they prayed for Daniel and his family, Prime Minister Tony Blair joined a host of well-wishers to send his sympathy to them and Daniel's family, who live in Ferryhill, County Durham.

Mr Blair broke off from a busy round of engagements across the North-East to say: "My thoughts and prayers are with the family at this very sad time.

"I was very sorry to hear of the tragedy and can only offer my sympathy to those who knew Daniel."

Inside the school, where Daniel died after a swimming session, classmates mourned the loss of the popular youngster.

Pupils were offered specialist support from counsellors from local education authority Durham County Council, St Cuthbert's Care and school staff on the last day of term.

Deputy headteacher Peter Coady said: "Pupils have all been offered counselling, and support will be available during the Christmas break.

"Some wanted to stay at home and deal with it in their own way, but others wanted to be together and remember Daniel at Mass.

"It was low-key and pupils laid flowers in his memory and wrote heartfelt messages in a book, which will be given to Mr and Mrs Readshaw."

Prayers were said for Daniel and his family.

An excerpt from one read: "Though we are saddened that our brother Daniel was with us for so short a time, we entrust him to you with confidence.

"May he live, radiant and forever young, in the happiness of your kingdom."

The other 23 youngsters who were in the pool at the time spoke to detectives investigating Daniel's death, along with the teacher who was supervising the session. Health and Safety Executive inspectors also started inquiries at the scene.

The schoolboy had been pulled from the pool after becoming distressed during a lunchtime swim, and despite frantic efforts to revive him was declared dead shortly after arrival at Bishop Auckland General Hospital.

Police said yesterday that although inquiries were at an early stage, there was nothing to suggest Daniel's death was in any way suspicious.

Following a post-mortem examination, an inquest was opened and adjourned at Bishop Auckland Court yesterday.

Home Office pathologist Nigel Cooper asked for more time for inquiries to establish an accurate cause of death.

The family have called for a thorough investigation to establish whether a hidden hereditary condition could be behind the deaths of Anne-Marie and Daniel.

Grandmother Kath Conroy, 60, said: "We need to know whether there is a link between his death and Anne-Marie's.

"We realise it is possible that they were caused by the same thing and we need to know for the sake of the other children.

"Anne-Marie was a very fit girl, she was a marvellous athlete and hadn't suffered any ill health.

"The only problem she'd had were a couple of fainting episodes, but they were put down to the normal process of growing up.

"At the inquest there was evidence that she may have had a fit, and we need to know whether there was something there we didn't know about with Daniel.

"He was a very slim, fit young lad. He wasn't an athlete like Anne-Marie but he was never in ill health.

"To lose him like this seems so unbelievable, it is like living the same nightmare twice."

Daniel's mother and father, Iain and Marie, have three other daughters, including ten-year-old Catherine, who is responding well to treatment for leukaemia.