National's finance spokesperson Nicola Willis is rejecting accusations she lied about internal tensions among Labour over its tax policy.

Willis claims Finance Minister Grant Robertson and Prime Minister Chris Hipkins had a disagreement over the start-date for Labour's promise to remove GST from fruits and veg.

Robertson denies that's true, but Willis says she was only providing a theory - after Hipkins said he would 'aim' to have the policy in place by 1 April.

"Why were their numbers put out that suggested the policy wasn't going to start until potentially October?"

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