The Greek unit of mobile giant Vodafone, has been fined Eur 76m (£50.9m) by a Greek privacy watchdog over a phone tapping scandal. The company has described the fine as “illegal, unfair and baseless” and vowed to fight the decision.

The watchdog – the Greek Communications Privacy Protection Agency – said Vodafone had failed to protect its network from hackers who monitored 106 mobile accounts.

“Vodafone’s Greek management team has fully co-operated with the enquiry and believes the decision to fine the company is completely unjustified,” Vodafone said Friday. The firm added that it supports its Greek management team’s decision to oppose the ruling “and to appeal against the decision.”

The company also said that the investigation was “incomplete” because it did not take into account Ericsson, which, it is alleged, supplied the wire-tapping software. The watchdog, meanwhile, said the investigation would continue and has asked Ericsson to testify at a later date. Ericsson, it is understood, has agreed to cooperate.

The fine follows the revelation in February that more than 100 people – including the Prime Minister Costas Karamanlis, senior military officers, journalists and activists – had their mobile phones tapped by hackers. It is believed the taps continued for over a year around the Athens 2004 Olympics.

Vodafone Greece alerted the authorities after it became clear its equipment was being used.

The family of the technician who was found hanging days after exposing the scandal, welcomed the watchdog’s decision. They believe the ruling will aid their campaign to find the truth about the death of Costas Tsalikides – Vodafone’s network planning manager. His family maintain he was murdered despite a ruling earlier this year which ruled out foul play.