John Key to attend Barack Obama's summit on countering Islamic State

Prime Minister John Key is to attend US President Barack Obama's summit on countering Islamic State in New York but said it will be the Trans Pacific Partnership he raises if he meets Obama one on one.

President Obama has called the summit to coincide with the leaders' week of the UN General Assembly, during which leaders of about 160 countries are expected to be New York - including Mr Key, the Pope and Russia's President Vladimir Putin who is attending for the first time in a decade.

Obama's summit on the sidelines will be attended by leaders of up to 60 countries which form a coalition involved in Iraq and Syria, including New Zealand which sent training troops to Taji in May.

In his speech to the General Assembly last year President Obama called on all leaders to report back this year on measures they had taken to stop the spread of extremism, both domestically and internationally.

Mr Key said it was important to attend the summit.

"Isil is a serious and growing threat to global peace and security and it is important world leaders continue to engage on the appropriate measures to tackle Isil and violent extremism more widely."

He did not expect to boost New Zealand's own involvement however.

He expected to talk with President Obama while in New York but that was likely to be a chat at the summit or a social function rather than a formal meeting.

His top priority for that talk would be the Trans Pacific Partnership after the countries involved fell short of an agreement at talks in Maui.

"Bluntly we want to just try and progress where we're going. I think we are getting fairly close, he's pretty instrumental in it all so that would be the main thing to talk about I guess."

He said it had been an important part of President Obama's work as he heads toward the end of his final term as President.

The General Assembly will also coincide with talks by officials and trade ministers in Atlanta to try to break through the remaining sticking points around dairy, automobiles, patents and intellectual property.

Mr Key said there had been discussion since then.

"I'm not quite so confident as to say I think a deal will be concluded at the UN or in the next week or two, but I think quite a bit of progress could be made."

While progress had been made in some sectors, there was not yet enough progress for New Zealand's liking in dairy.

"We are a long way away from saying we are at the best place we can be for dairy. I still remain confident that in the end we'll settle in hopefully the right place for dairy or at least it will be the best we can do."

Mr Key last attended the leaders' week in 2013 and this is his first time since New Zealand was elected to the Security Council.

He said it would also provide a chance for talks with his international counterparts on the priorities for the Security Council and calls for its reform, which New Zealand backs.

Russia is chairing the Security Council until the end of September and the United States has criticised Russia for its support of the Bashar al-Assad regime in Syria.

This week, US Secretary of State John Kerry appeared to soften his position on Assad, saying the US was open to his regime staying on for an 'interim' period, and called on Russia to try to bring Assad to the negotiating table.

Obama also hosted an anti-extremism summit in February - the week before Mr Key announced details of New Zealand's deployment to train Iraqi forces in Iraq.

That was attended by New Zealand's Attorney General and minister of the spy agencies, Chris Finlayson.