Labour MP Rachel Boyack has expressed her regret after walking behind a march chanting the controversial "from the river to the sea" declaration, explaining her actions were to ensure the safety of two opposing marches happening at the same time.

Boyack spoke to Newstalk ZB Plus following reports the Nelson MP had been spotted at the rally over the weekend, where protestors chanted a phrase considered by the Jewish population as one of antisemitism.

According to Boyack, she was at her regular stall at the Nelson Market when she noticed a potential clash between an Israeli protest and a pro-Palestinian protest, both occurring at the same time and looking likely to intersect.

"To prevent this, I went to the organisers of the Palestine rally and asked that they take a different route," she told ZB Plus.

"The march was already underway and while the chant in question was used while I was there, I did not join in, nor do I condone its use and I walked back to my stall."

Boyack then stated she regretted walking behind the protesters while the chant was used and the inference of her support for antisemitic views.

"I stand against all forms of racism, including antisemitism and islamophobia," the Nelson MP said.

"In the past weeks, I have met with both the Palestinian and Jewish communities to hear from them regarding the current conflict in Gaza. Like many, I have a long-held desire for lasting peace in the region."

This follows an apology from Green Party MP Chlöe Swarbrick, "to those who have felt [offended]" by her use of the same chant called divisive and inflammatory by academics and political and community leaders.

Online reaction to Swarbrick's apology was mixed, with one X user posting that it was the "worst apology ever" and another posting "so she's 'sorry, not sorry' then".

Acting Prime Minister and Labour leader Chris Hipkins called the phrase "loaded" following Swarbrick's actions and he expected that Labour MPs would also not use the phrase.