Police are investigating the suspected deliberate contamination of a number of snack food packets, believed to be potato chips, at a Melbourne supermarket last week.

A police spokeswoman confirmed officers were working with the Department of Health and the manufacturer to determine whether the contamination was deliberate.

A caller to 3AW's rumor file today claimed that pins, needles and paper clips were found inside three packets of chips in the supermarket.

The police spokeswoman could not confirm the location of the supermarket or any further details about the investigation, however said the "safety of consumers is paramount."

No public health warning has been issued.

A Melbourne restaurant has been fined $20,000 after an inspector found its kitchen infested with cockroaches, rodent droppings and accumulated grease, dirt and food waste.

A director of Ten Ren's Tea Station agreed to temporarily shut its upstairs kitchen on March 7 this year - after a complaint from a customer - when authorities feared for public health.

Senior magistrate Dan Muling yesterday said there was no justification or excuse for the conditions and told its directors they ''wouldn't have your own kitchen looking like this''.

Prosecutor Sebastian Reid said the initial inspection revealed the kitchen to have ''heavy infestation'' of cockroaches, some rodent activity and no method to sanitise food contact surfaces and utensils.

Mr Reid listed more than 30 examples of Food Act breaches to walls, the floor, bowls, fridges and freezers, shelves, door seals, handles, exhaust hood and microwave oven.
These included a high number of live and nesting cockroaches, rodent droppings and heavy accumulation of grease, dirt, food waste and rubbish on the floor, under fridges, cooking equipment and kitchen benches.

Defence barrister Tim Bourke said the directors started the restaurant in 2008 and had employed unreliable students and migrants.

That’s me and Melbourne Milton, having a chat along Southbank one morning last year when we visited Australia. The Crown Casino is tucked in behind us. We spent a couple of nights in the hotel – it was great.

But it wasn’t so great for 160 employees of superannuation fund Unisuper, who decided on a Christmas party at the casino and are now dealing with what appears to be food poisoning.

Unisuper spokesman Paul Murphy said most of those who had been ill after the party appeared to recover within a day or so of becoming sick.

But one Unisuper manager said he was still feeling ill almost a week later. ''I wish I hadn't eaten that bloody seafood,'' he said.

Crown spokesman Gary O'Neil yesterday confirmed government food inspectors had visited on Tuesday to investigate what he believed to be the casino's first complaint of possible food poisoning.

He said the inspectors assessed kitchen preparation areas and found no issues of concern. Food samples have been taken away for testing.

A North Melbourne bakery riddled with cockroaches and mouse droppings that failed to comply with an order to clean the shop has been fined $7,000.

After an inspection in April last year that found a live mouse, cockroaches, moths, mouse droppings and dirty shelving and work benches, Queensberry Hot Bread's owner Dino Primitivo did not comply with an order to clean the shop or deter pests, the Melbourne Magistrates Court heard yesterday.

Photographs tendered to the court showed a live mouse under shelves, clothing hung up to dry in front of an oven, cracked, broken and dirty work tools, benches and surfaces, and mouse droppings on the floor.

Magistrate Sue Wakeling told Primitivo,

"If you cannot offer food that is safe for consumption, you ought not to."