Low-cost supermarket Lidl's handling of the row with Mark Quinn of Sallins, Co Kildare, was described by the tribunal as "unacceptable and inexcusable".

While the German-based Lidl does not recognise trade unions in Ireland, the shopworkers' union, Mandate, said that a ban on workplace affairs among managers was common in shops 10 years ago. Standard practice was that one of the secret lovers would be transferred to a distant outlet if the affair persisted, but it was very rare in today's retail sector, said a Mandate spokesman.

Quinn told the tribunal that when he admitted to another manager that he was having an affair with a colleague, he was told that he was "throwing away his career", and that there was nothing could be done for him when the board found out.

But Quinn was later told by a more senior manager that the MD "had given them his blessing" and that the relationship would not affect their careers.

He subsequently found out that at the same time his girlfriend was being questioned by the MD about the affair. At the tribunal, the girlfriend said that the MD told her that she or her boyfriend would have to leave and they "were not to be seen together, even privately".

Quinn also told the tribunal that he frequently worked 12 to 16-hour shifts, seven days a week, and had suffered chest pains and dizzy spells. On one occasion, he finished a shift at 2.30am and was told to come back in at 6.30am. When he arrived in 10 minutes late, he was reprimanded.

Mainly based in Newbridge, Co Kildare, Quinn was sent to Lidl's store in Buncrana, Co Donegal to investigate a problem with 'sweet-hearting', a practice where the price-scanner is switched off and items are not registered at the till.

Quinn reported he had found no evidence of 'sweet-hearting'. When he told his superiors that the shop closed early on Sundays, he was told to sit outside in the car park after the shop shut until it was time to go home.

The tribunal said that Quinn had worked "a ridiculous number of hours" without praise or encouragement, and had had "very little option other than to discontinue with his employment."