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.

The two countries were called “like family”, at a pre-Anzac Day commemoration in New Zealand’s capital Wellington including Mr Key and Prime Minister Tony Abbott.

“We always say a strong Australia is good for a strong New Zealand,” Mr Key told reporters, adding that falling iron ore prices were outside the Abbott government’s control.

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He said Australia was New Zealand’s largest source of foreign investment and tourists.

New Zealand is often the first country which Australian companies expand to after a 1983 Closer Economic Relations agreement paved the way for a nine per cent increase in bi-lateral trade across the Tasman, news.com.au reports.

“The CER has delivered to Australian businesses another market roughly the size of Queensland, Johnny Weiss, CEO of the Trans-Tasman Business Circle said. “It’s widely seen as one of the most successful free-trade agreements in the world.”

Mr Abbott praised the relationship between the two countries that weathered the “baptism by fire” of World War One’s Gallipoli landing to continue cooperating in military capacities such as the two nations sending a fresh contingent of 330 Australian troops and 100 from New Zealand to train Iraqi forces.

“It obviously is a remarkable thing to look back 100 years to the terrible baptism of fire that our two countries had on the Gallipoli Peninsula,” he said.

“It is quite fitting that 100 years on, Australia and New Zealand are again working for our values and our interests together in Iraq in the Building Partner Capacity mission that we are jointly engaged upon and will shortly be operational in the Middle East,” The New Zealand Herald reports.

—with AAP