On Tuesday Westpac said it had begun a process, which was the result of customer feedback, that would involve it exiting munitions investments.
"The process is under way and will be completed as soon as is practicable," Westpac said in a statement.
"Any exposure by Westpac KiwiSaver to companies that are involved in the manufacture of cluster bombs, landmines or nuclear explosive devices is not direct."
On Wednesday, ANZ - the country's biggest KiwiSaver provider - told Radio NZ that none of its funds held direct investments in cluster bomb makers.
But ANZ's investment board had voted this week to exit any direct holdings in companies that made "controversial" weapons including anti-personnel mines and nuclear armaments.
ANZ would also dump direct investments in tobacco companies and was considering exiting passive funds that had exposure to weapons firms.
A BNZ spokeswoman said the bank's KiwiSaver funds did not have any investments in cluster munitions or landmine manufacturers.
"We understand we have a small indirect exposure to companies involved with nuclear devices," she said. "We are currently reviewing this and considering excluding these investments."