Jacinda Ardern meets German Chancellor Angela Merkel for trade talks

German Chancellor Angela Merkel says Kiwis should "be proud" of Jacinda Ardern after what she described as an "interesting and fun" first meeting with the Prime Minister.

Free trade agreement talks with the European Union are heating up, as Ms Ardern meets with leaders in the region.

The Prime Minister met with Ms Merkel in Berlin on Tuesday night (NZT), before heading to London.

She was given a red carpet and military welcome ceremony as she arrived in Berlin.

The two leaders discussed trade, international relationships and the Syrian conflict.

Ms Merkel was asked about how the meeting had gone, which Ms Ardern translated.

"They want to know if you found me likeable".

"Time flew and it was nice," Ms Merkel replied.

"It was very interesting and fun. So you can be proud of your Prime Minister. If you want to write this down for the New Zealand press. This will be the headline in the morning papers I trust."

The meeting comes as the US signals it wants to join the CPTPP after pulling out last year.

"If the United States wanted to follow through on their interests, that would trigger a renegotiation as it would if others were interested in joining the agreement as well," Ms Ardern says.

She remains adamant the EU supports her stance on military airstrikes in Syria, despite her decision not to fully back military action or expel Russian diplomats.

"Our view is that we need to be able to maintain dialogue as an international community to ultimately resolve these issues," Ms Ardern says.

"We have called Russia into account, as have others, around the role that they play as a supporter of the Assad regime and we will continue to do so.

"New Zealand from the very outset has called on Russia as a country with influence in this area to hold to account the regime around the use of chemical weapons."

She's now travelling to London for the Commonwealth Heads of Government Meeting from Wednesday.

The EU is due to discuss the mandate for the New Zealand European Union FTA at a meeting later next month.