New Zealand PM Jacinda Ardern helps out a fellow mum

New Zealand Prime Minister Jacinda Ardern (pictured) confirmed Thursday she paid for a harried mother's groceries in a gesture sure to enhance a reputation already soaring because of her response to the Christchurch mosque attacks.

Ardern was reluctant to discuss the incident, revealed on social media, involving a mother-of-two who was ahead of the prime minister at a supermarket checkout when she realised she did not have her purse.

"(Ardern) paid for my friends' shopping in the supermarket the other day when she had forgotten her purse and had two screaming kids in tow," Twitter user Helen Burness posted, adding: "like we didn't love her enough".

Ardern swiftly wrapped up a media appearance Thursday when asked why she had helped the woman, replying only, "because she was a mum".

The 38-year-old had her own daughter Neve last June, becoming only the second prime minister in the world to give birth while in office, and later taking the infant onto the floor of the UN Assembly in New York.

She has won widespread praise for her response to the March 15 Christchurch attacks in which a white supremacist gunman is accused of killing 50 Muslims in an atrocity that shook the normally peaceful nation.

The New Zealand Herald has described her actions as a mix of "solace and steel" after she donned the hijab while comforting devastated families and also moved swiftly to tighten gun laws.