It was the relish – not the rabbit, chicken or pork terrine – that caused 38 corporate diners to keel over vomiting at the Melbourne Cricket Ground on ANZAC Day, an investigation has revealed.

The Department of Health found food poisoning was most likely behind the gastrointestinal illness outbreak that suddenly gave dozens of suited-up diners fever and diarrhoea at the official President’s Lunch function.

“The evidence gathered during the investigation… revealed that the most likely source of illness was the relish which was served with the entree of rabbit, chicken and pork terrine,” Victoria’s Chief Health Officer Dr Brett Sutton said in a statement on Tuesday.

The department ruled out chemical or environmental exposure as possible causes.

The revelation comes after a number of independent tests of the terrines by the MCG, the Department of Human Services and catering company Epicure were all inconclusive.

For months, the source of the chaos that unfolded at the Olympic Room had remained a mystery.

It is understood seven people became so seriously ill they were sent to hospital from the MCG.

A situation room was set up to assist paramedics.

-with AAP