The inquiry will be held in a Christian centre in Motherwell and is expected to last weeks if not months.

The proceedings will be presided over by Sheriff Principal Graham Cox QC, Sheriff Principal of South Strathcylde.

Twenty people, most of them elderly, died in the E. coli 0157 poisoning outbreak in Lanarkshire in late 1996 and early 1997.

Some of the victims were elderly people who attended a Wishaw church lunch for local pensioners.

An elderly woman in a nursing home in Banknock, central Scotland, became the 20th person to die, making the outbreak the worst on record.

Butcher was cleared

E-coli growing in a petri dish

Butcher John Barr, whose shop in Wishaw was implicated in the outbreak, stood trial last October accused of culpable and reckless conduct over the supply of cooked meat.

The case collapsed and he was formally acquitted.

In January the shop business partnership of John Barr and Son was fined a total of �2,250 for food hygiene and safety breaches.

That hearing, in which the partnership pleaded guilty, was told 160 people were admitted to hospital at the peak of the outbreak.