Three British nationals in the UK have been infected with E.coli linked to the German outbreak, according to the Health Protection Agency (HPA).

It brings the total number of cases in the UK to seven. Four cases are among German nationals.

Experts believe all the patients caught the infection in Germany and brought it back to the UK.

Three of them have developed the potentially deadly complication of haemolytic uraemic syndrome (HUS).

According to the World Health Organisation (WHO), cases of HUS and enterohemorrhagic E.coli (EHEC) continue to rise in Germany. Overall, 10 countries have now reported cases to WHO.

Nine patients in Germany have died of HUS and another six of EHEC. One person has also died in Sweden, bringing the total number of deaths to 16, according to the latest figures from WHO.

Many other patients are in hospital, with several needing intensive care, including dialysis.

Overall, more than 1,600 cases of complications linked to the E.coli outbreak have been reported worldwide. All cases except two are among people who had recently visited northern Germany and in one case, the person had contact with a visitor from northern Germany.

In England, there have been four new cases overall, including three among Britons. The other new case is of a German national on holiday in England.

The exact source of the contamination has not yet been determined, according to the HPA and WHO. The Food Standards Agency has found no evidence so far that produce from possible sources has been distributed in the UK.