Nicky Hager feels his rights have been breached, following revelations Westpac Bank gave police personal information from his accounts.

Detectives looked into his travel history, phone records and even a TradeMe account as part of an investigation into the hacking of Whale Oil blogger Cameron Slater.

It's now been revealed Westpac Bank offered up nearly 10 months worth of transactions without a court order.

Mr Hager says he intends to seek a full and frank disclosure of the extent of the breach from Westpac.

His case before the High Court includes a claim against police for seeking and obtaining information without the legal green light.