It could take three years to make changes to the welfare system such as removing excessive benefit sanctions, the social development minister says.

Photo: RNZ / Daniela Maoate - Cox

Carmel Sepuloni told TV3's Newshub Nation she was setting up an expert advisory panel to report back before any changes were made.

Beneficary advocates have recently renewed calls for a culture change at the Ministry of Social Development.

Prime Minister Jacinda Ardern has also echoed those views.

However, Ms Sepuloni said the ministry was like a jumbo jet that had been steered for nine years in a certain direction.

Expecting her to undo "nine years of neglect" under the National-led government immediately was unreasonable, she said.

However, the ministry was already making internal changes.