Abu Dhabi Commercial Bank has at least $500 million in exposure to troubled Saudi business groups Saad and Algosaibi, a banking source said on Wednesday.

"ADCB has significant exposure to the Saudi businesses. It could be easily over $500 million," one banking source told Reuters, declining to be named due to confidentiality reasons.

Chief executive Ala'a Eraiqat declined to comment on the nature or the magnitude of any possible exposure but said it was mostly backed up with cash deposits held at ADCB.

"The majority of ADCB exposure to troubled Saudi financial institutions is covered by cash deposits held with us. We are in close contact with them and working with their financial advisers and the rest of the lenders for a speedy resolution," Eraiqat told Reuters.

"I cannot comment on the amounts or give any more details," he said.

Rival First Gulf Bank has a small amount of exposure to the troubled groups, another banking source said on condition of anonymity.

"Although not significant, First Gulf Bank has some exposure," the source said.

First Gulf declined to comment to emails and telephone calls.

Saad Group and Ahmad Hamad Algosaibi Group & Bros. have said they are restructuring their debt, with reports putting the amount at around $10 billion.

Abu Dhabi's largest bank by assets, National Bank of Abu Dhabi has said it has "negligible" exposure to the Saudi groups. - Reuters