A year-long investigation into a salmonella outbreak following a Jewish wedding which may have led to the death of the bride's great-aunt has not proved a link to the kosher caterers.

Scientific tests last October suggested a teriyaki salmon and bean sprout dish from Manchester's Shefa Mehadrin caterers caused the outbreak, which saw 10 guests fall ill with a rare strain of salmonella in August 2010.

Rene Kwartz, 82, from Crumpsall, is thought to be the only person who died during a national outbreak of the strain, blamed on infected bean sprouts from China, which affected 241 people across the UK.

The Health Protection Agency's report into the national outbreak, published on Wednesday, concluded that the teriyaki salmon dish was "the most likely vehicle of infection". But an epidemiological study into the Greater Manchester outbreak had not found evidence to prove the bean sprouts served at the wedding were the source of infection.

Microbiological tests of Shefa's premises also found no evidence of salmonella and the report noted that wedding food was supplied by two other companies.

The HPA said its investigators had found some Manchester caterers of Jewish functions which were not properly registered with local health inspectors.

They "had neither a documented food safety management system nor adequate evidence of training in food hygiene". The caterers were not named in the report.

A full inquest into Mrs Kwartz's death is due to be heard by the coroner later this year.