Westpac Banking Corporation (ASX: WBC) has extended its infrastructure outsourcing relationship with IBM for another five years. The bank's initial contract with IBM was signed 10 years ago for an initial total value of $2.3 billion.

The new contract would commence on December 1 and initially involves "little change in IT spending" for Westpac, the bank said in a statement on Monday.

IBM will retain prime responsibility for operating Westpac's key infrastructure services, including data centre, mainframe, midrange, storage, desktop, print and security operations.

"The flexibility of the contract will assist in delivering improved efficiencies through the implementation of new technologies and the completion of the Strategic Investment Priorities programs," the bank said.

The new IBM services contract would "drive a very different relationship and set us up for the future"said Westpac's group executive technology Bob McKinnon.

"This new relationship will support the significant IT investment program underway within the Westpac group to improve our customer touch-points and support our multi-brand model," he said.

The bank did not disclose the size of the new contract, but the Australian Financial Review said the deal was worth $1.3 billion

Westpac, which also has outsourcing agreements with HCL Australia, Telstra, Fiserv, and HP subsidiary EDS, said it would take "greater accountability in the design and management of IT services", using other suppliers or solutions where appropriate.