New Zealand Prime Minister John Key said China may eventually surpass Australia to become his country's biggest market for exports as Asian economies drive global economic growth while Europe struggles.

New Zealand's free-trade agreement with China has been "hugely successful" since it was signed in 2008, Key said in response to a question posed after giving a speech in Sydney on Thursday.

"We see huge opportunities in China," he said. "We think it's worked really well for us."

New Zealand's exports to China are increasing four times faster than its shipments to Australia.

China Daily?- Agencies