Trade Minister Tim Groser says New Zealand must strengthen economic ties with Indonesia, New Zealand Herald reports.

Even as Mr Groser acknowledged "some problems" within Indonesia, he stressed Indonesia was a fully democratic state and hinted New Zealand should look closely into opportunities with the fast-developing Southeast Asian nation.

Mr Groser made the remarks to reporters on Sunday in Darwin in transit to Jakarta.

"Yes, you've got numerous problems but it is absolutely a democratic country," he said.

Mr Groser noted per capita income in Indonesia, where population is at 240 million, is currently at somewhere between US$3000 and US$4000. He also considered the country's GDP growth of 6 per cent a year compounding, and said Indonesia's economy was reaching "a point of inflection."

"We're going to Indonesia at a time where from now on these increments of economic growth change the whole game. There will be enormous implications for Australia and NZ," he said.

Indonesia's GDP is close to US$1 trillion, and the Asian Development Bank estimated that by 2050 Indonesia's economy would be worth US$11 trillion - a figure twice the current size of the Chinese economy.

Meanwhile, Prime Minister John Key arrived in Jakarta Sunday night with a delegation of key New Zealand business leaders for a formal call on Indonesian President Susilo Bambang Yudhoyono.

Mr Key will speak at a New Zealand-Indonesia business conference Monday morning, after which he will meet with the Association of Southeast Asian Nations' secretariat.

The Green Party has criticized the prime minister's Indonesian visit, with Green Party MP Catherine Delahunty saying the government is seeking "trade at any price" amid alleged human rights abuses in the disputed territory of West Papua.

"We hear constant concerns about Fiji and now he celebrates democracy in Indonesia. It's the height of hypocrisy to talk about trade and democracy while ignoring human rights abuses," Ms Delahunty told the Herald.