The Garda Bureau of Fraud Investigation has started an inquiry into an alleged irregularity at Vodafone following the dismissal of a senior member of the finance team at Ireland's biggest mobile phone company, writes Arthur Beesley, Senior Business Correspondent.

Vodafone referred the case to the Garda after an internal investigation into the alleged misappropriation of a large sum of money. Reports that as much as €1 million was involved were not denied by the company.

The alleged irregularity was linked to procurement activities in Vodafone. Customer accounts were not involved, Vodafone said yesterday.

The Garda declined last night to comment on the investigation, which is believed to be at an early phase only. However, it is understood that the man in question worked at the headquarters of Vodafone Ireland at Sandyford, south Dublin.

He was suspended for the duration of Vodafone's internal investigation into alleged "inappropriate behaviour", which is now complete, and dismissed in March.

No other employee is under investigation at the moment.

"An employee has been dismissed," said a Vodafone spokeswoman. "The company will be making no further comment at this stage as the matter is subject to legal proceedings. The company confirms, however, that the matter has had no impact on customer accounts."

It is understood company has informed its 1,800 staff at Sandyford of the situation.

Although it is not yet clear whether Vodafone will take any civil proceedings against the man, this is a possibility. The company's next course of action may be determined by the outcome of the Garda investigation.

It is not known whether Vodafone learned of alleged irregularities as a result of an internal or external audit, suspicious behaviour or a "mistake" by the man that uncovered his activities.