eBay faces investigations on both sides of the Atlantic after a cyber attack breached one of its databases housing information on 145 million users, Digital Spy said.

The UK's Information Commissioner's Office (ICO) is working with European data authorities with a view to taking action against the e-commerce giant, while three American states are launching their own probes.

Data protection laws prevent the UK watchdog from taking action without the involvement of the Luxembourg data protection, where eBay's European headquarters is based.

"There's millions of UK citizens affected by this, and we've been clear that we're monitoring it, but by taking the wrong action under the law now we risk invalidating any investigation," an ICO spokesman told BBC News.

The company contacted customers earlier this week advising them to reset their passwords to safeguard themselves from the hack, which occurred between late February and early March.

eBay has been criticised for its late response, but the firm insists that there have been no instances of customer accounts being accessed by hackers.

Reports that large quantities of eBay data have appeared on anonymous text website Pastebin have been denied by the auctioneer.