The makers of Valium have urged a global recall of all 5 milligram packets of the tablets after evidence of tampering.

Manufacturer Roche recalled all packs of 50 Valium 5 milligram tablets last week after it was revealed that a worker at its Sydney distribution centre had been swapping out the relaxant for different drugs.

“If a patient has an affected pack, there is a risk that they will not have adequate supply of their medicine and could take the incorrect medicine, which could have serious health consequences,” a statement from Roche says.

“I am not sure how many patients would be affected, but it's important that the packets are returned and that patients seek medical advice,” Svend Peterson, Roche Products managing director said.

The Therapeutic Goods Administration (TGA) issued a recall on Friday.

“It has been identified that blister pack sheets containing other medicines have been substituted into some packs of Valium 5 mg tablets,” the statement said.

“These medicines may include (but may not be limited to) BTC Paracetamol Codeine tablets, BTC Rosuvastatin 10 mg tablets and Apotex-Pantoprazole 40 mg tablets.

“If a patient has an affected pack, there is a risk that they will not have adequate supply of their medicine and could take the incorrect medicine, which could have serious health consequences.”

Symbion Contract Logistics – which runs the Sydney distribution centre – says it has sacked a worker at the facility over the issue.

Symbion Contract Logistics describes itself as the “most efficient and extensive distribution system for manufacturers in the Australian pharmaceutical industry”.

“The Matter has been referred to NSW Police,” a spokesperson for Symbion said.

“While we are confident this was an isolated incident affecting only a small number of blister packs, patient safety is our absolute priority and we are working together with our partners to ensure the ongoing integrity of the supply chain.”

NSW Police are investigating.