Up to 3,000 customers received a letter from Vodafone today informing them sensitive personal information could have been leaked after documentation held by the company was found dumped in a skip.
The problem was discovered when Person 2 Person, a former agent for mobile operator Eircell which Vodafone bought out in May 2001, cleared out its offices after relocating to new premises.
A Vodafone spokeswoman said the data leak was discovered 10 days ago but the company forced to delay a public announcement due to extensive manual cross-checking required to establish which customers were effected.
The documents in question are missing application forms for pre-paid mobile phone contracts processed by Person 2 Person for Eircell.
The spokeswoman said the investigation was carried out in association with the Gardai, the Data Protection Commissioner and various financial institutions.
She also claimed any legal action arising out of the leak "was highly unlikely".
This afternoon, Mr Tommy Broughan TD, the Labour spokesperson on Communications and the Marine, called for an immediate and "full investigation into the circumstances surrounding the dumping of sensitive information".
He added: "It's absolutely outrageous that people's personal details including bank and account information were tossed out into a skip when they should have been stored safely and securely."