More than 200 rescue workers continued to comb through the wreckage to ensure that they have not failed to find any victims who were not among the list of people reported missing after the rink of the roof caved in under heavy snow on Monday.

"There are still areas that we have not managed to search," said Bavarian state authorities spokesman Christoph Abress, adding they hoped to complete the gruelling task later Thursday.

Until then a catastrophe alert would remain in place.

The death toll reached 15 overnight when the body of a woman was recovered from the debris after three days of search operations often hampered by heavy snowfall. Her husband was among the survivors of the accident.

Twelve of the victims were children or teenagers, and the other three all women of around forty. All of them were from the region.

Thirty-four people were injured in the accident and some 13 of them remained in hospital but their lives were not in danger.

The grim accident has touched Germans and left many asking how this could have happened in an area that is accustomed to heavy winter snow storms.

"Why?" one woman simply wrote in an Internet book of condolences that has been set up by local authorities and signed by more than 2,300 people.

Bild newspaper on Thursday published photographs of smiling girls skating in the rink shortly before the collapse, while one of the survivors, teenager Elfriede Datz, told television she simply remembered a "big noise".

"My only thought was get out," she said from hospital.

Authorities in the nearby town of Traunstein are investigating the circumstances surrounding the collapse of the rink's roof, which dates from

But a spokesman for the prosecutor's office said on Thursday that it could take months to establish the cause of the accident.

"Only then will we be able to see whether anybody is personally responsible. We cannot charge anybody until we know what caused the accident," spokesman Volker Ziegler said.

The mayor of Bad Reichenhall, Wolfgang Heitmeier, on Thursday told a press conference that a certificate issued in 2003 by local authorities stated that the roof of the building presented no risk.

"The structure of the roof ... is in a state which could be described as good," Heitmeier quoted from the document.

It added that there were signs of water damage but that these did not signify that there were any weakness in the structure.

According to reports by the local meteorological services, there was at least 180 tonnes of snow lying on the roof before it collapsed onto skaters on Monday, just 15 minutes before the rink was due to close for the day.

Adding to the confusion about the circumstances of the collapse, a local ice hockey club coach, Thomas Rumpeltes, has said he was told the snow was to have been cleared from the roof shortly before it caved in.

Rumpeltes said he had cancelled a practice at the rink for a youth team because the authorities had told him of the impending clearance shortly before the accident.

But he said no one had warned of any risk of the roof being unstable and it seemed that the snow removal was only a precautionary measure.

Pope Benedict XVI, who was born in the state of Bavaria, on Wednesday sent a telegram to the archbishop of Munich to express his condolences.

He said his thoughts were with the relatives after "the tragic accident which cost the lives mostly of children."

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