Key worried about Aust economy slowing

New Zealand Prime Minister John Key has praised the Abbott government's efforts to drive economic productivity and watch spending.

New Zealand PM John Key (R) has expressed concerns about a slowdown in Australia's economy. (AAP)

New Zealand Prime Minister John Key has expressed concerns about a slow down in Australia's economy and its roll on effect across the Tasman.

Mr Key made the comments while hosting Prime Minister Tony Abbott in Wellington for pre-Anzac Day commemorations.

"We always say a strong Australia is good for a strong New Zealand," he told reporters, adding that falling iron ore prices were outside the Abbott government's control.

Australia was New Zealand's largest source of foreign investment and tourists.