A rare strain of E. coli O157 is behind the infection outbreak linked to a children's nursery in Dunfermline, Fife, experts confirmed yesterday.

Doctors at Health Protection Scotland (HPS) said the organism had been seen in Europe and Australia but only a handful of times in the UK.

The strain has so far infected 13 people associated with the Careshare nursery at Lauder College. Four children were taken to hospital for treatment.

HPS said only four other single cases of the strain had ever been identified in Scotland, with four instances south of the border. Doctors are now trying to determine the origin of this latest outbreak. It is thought it was the result of bacteria spreading from person to person. A further 10 people linked to the nursery are awaiting test results.

Two children taken to hospital as a result of the infection are still being treated at Glasgow's Yorkhill hospital, where they are continuing to show signs of improvement.