John Key is optimistic a free trade agreement with Saudi Arabia could be in for revival.

The Prime Minister is in New York where he'll address the United Nations General Assembly and chair the Security Council this week.

LISTEN ABOVE: NZ Herald Political Editor Audrey Young speaks with Rachel Smalley

NZ Herald Political Editor Audrey Young said he's also been having bilateral meetings - including with the Saudi Deputy Prime Minister, the Pakistan Prime Minister and the European Council's president.

She told Rachel Smalley Mr Key said the Saudi meeting focussed on the trade agreement negotiated back in 2009.

"But has been stalled for some time and he revealed that Todd McClay, the Trade Minister, is off to Riyadh next week.

"So there's clearly some movement going on behind the scenes."

Mr Key will today meet with British Prime Minister Theresa May, where Helen Clark's bid for the top job at the United Nations will be high on the agenda.

The leaders of the five permanent UN members are normally off-limits for meetings on the subject.

But Helen Clark has been able to meet them through her current role with the UNDP.

Audrey Young said one she hasn't yet crossed paths with, is Theresa May.

"But Key will be talking to Theresa May about her candidacy, and also Clark is going to be meeting Boris Johnson, the next Foreign Secretary from Britain, who'll be here in a day or two."

SEE ALSO: Govt optimistic of Syria progress, despite shaky ceasefire

Tomorrow, John Key will address the entire UN General Assembly, ahead of chairing a Security Council meeting on Thursday.

Audrey Young said while it's a big moment for the Prime Minister, he's likely to stick to fairly general comments in tomorrow's speech.

"I guess it is possible he will raise the issue of United Nations reform and Security Council reform, but they tend to be fairly general speeches."

Thursday's Security Council meeting will see Mr Key stand front-and-centre to chair talks on the escalating situation in Syria.