UPDATED 3.21pm: About 2000 protestors turned out in Auckland this afternoon to send a message to the government about their opposition to New Zealand signing up to the Trans-Pacific Partnership.

AUDIO: Rachael Le Mesurier talks to Josh White about the nationwide TPPA protests.

They marched from Aotea Square to the US Consulate where a silver fern flag was set alight and burned.

Marches are underway in 17 towns and cities.

TPPA critic Professor Jane Kelsey from the University of Auckland spoke at the protest. 

Oxfam executive director Rachael Le Mesurier is among those demonstrating.

She says trade isn't just about import tariffs and export volumes.

Le Mesurier adds it impacts on our ability to buy medicine, legislate on things like tobacco, and tax international companies.

She says transparency in negotiations is vital, given New Zealand's reliance on trade.

Wellington:

Around 1000 protestors have filled Wellington's Civic Square - and 16 other public places around the country.

Newstalk ZB reporter Laura McQuillan says their message is clear.

She says there are speeches happening, as well as many flags and signs calling for an end to the TPPA.

Laura McQuillan says there's also a bit of a party atmosphere, with bands and music.

At least 2000 protestors have also turned out at Auckland's Aotea Square.