Water contaminated with E.coli bacteria and sapovirus has sickened at least 36 people and possibly more in a posh department store in the centre of Ljubljana, mostly staff but also members of parliament and employees of the country's largest bank.

The Maximarket department store detected an infection of unknown origin among its customers and staff on 15 April and notified the Ljubljana water utility Voka Snaga immediately and banned the use of tap water for food and drinking. The public did not learn about the incident until two days later.

Samples of water taken from the building's mains system confirmed the presence of sapovirus and E. coli, according to epidemiologist Eva Grilc of the National Institute of Public Health (NIJZ).

Hospitals are not seeing an increase in patients so far, but Grilc said more people could seek medical aid as problems can occur days after ingestion of contaminated water or food, and usually last for several days.

The NIJZ has so far been contacted by more than 70 people about the issue since it opened a dedicated phone line.

Maximarket is located in the immediate vicinity of Parliament House and the headquarters of NLB, Slovenia's largest bank. Its multiple eateries are a popular meeting place for politicians and businessmen.

The Food Safety, Veterinary Sector and Plant Protection Administration said two of the eateries, Maxi Brunch Cafe and Moji Štruklji Maxi Restaurant, are currently shut down while the Maximarket grocery store and the Dobnik chocolatier shop sell only pre-packaged products.

All four are connected to the Maximarket water system.