New Zealand and the European Union have agreed a free trade deal, following four years of talks.

Prime Minister Jacinda Ardern said the deal would help boost exports to the EU by an annual $1.8 billion by 2035. However, earlier in the week Ardern said she was "very willing to come away from Europe without final conclusion" if substantial market access wasn’t included.

Yet discussions between New Zealand's chief negotiator Vangelis Vitalis and trade minister Damien O'Connor concluded a matter of hours before the Prime Minister was set to leave Brussels on Thursday.

"Despite many challenges, we got there, and today we deliver an agreement that represents improved trade opportunities for our exporters," Ardern said, as the deal was unveiled with European Commission President Ursula von der Leyen.

When the agreement comes into effect, 91% of tariffs will be removed, and 97% will be eliminated by year seven, reports the New Zealand Herald.

The trade minister said they did "very very well" to seal the deal, which will represent massive opportunities for New Zealand exporters.

"This is the best opportunity we've had and the best deal we can get for a very long time. Of course we didn't get everything that everybody wanted, but that's a trade deal," he told AM this morning.

"Obviously we have heard some comments from a couple that are disappointed with the volumes, but they get far better access than they've had, and we can work on that," he added.

O’Connor continued: "We made progress and $1.8 billion of value after year seven - that's worth fighting for."

In regard to the meat and dairy industry, the trade minister said they had secured the best possible deal: "We went literally to discussions five minutes before we were at the announcement on issues. We fought hard and negotiators did right up to the last minute. We extracted a bit more value even in the last half hour of the agreement for our side.

"But ultimately, this is a compromise. This is an agreement on trade and there are multiple interests in both sides of the agreement and we just have to reach a final conclusion."

The deal could come into effect within 18 – 24 months, subject to European Parliament and EU governments’ approval, Reuters news agency reports.

Bernd Lange, chair of parliament's trade committee said it was a good day for trade, and the deal was one of the most advanced in regard to the environment and labour rights.