U2 rocker Adam Clayton has told how he was stunned when he discovered his personal assistant had allegedly stolen $3.8 million from him.

Carol Hawkins is on trial at Dublin's Criminal Circuit Court in Ireland charged with 181 counts of theft stemming from her time working for the bassist.

The mother-of-two, who was a signatory on Clayton's chequebook during her employment, is accused of transferring huge sums of cash from his funds to her bank account between 2004 and 2008. She denies the charges.

Giving evidence on Thursday, Clayton told the court he was shocked to discover his loyal employee, who worked for him for 16 years, allegedly betrayed him.

He said, "She had my absolute trust. We had been together a long time - working together. She had been very conscientious. I felt she looked after my money and on many occasions accused others of being greedy so I was extremely surprised."