New Zealand's Jacinda Ardern to quit as PM next month

New Zealand's Prime Minister Jacinda Ardern plans to stand down no later than early February and will not seek reelection, Ardern has said in a televised statement.

Fighting back tears she said on Thursday the general election will take place on October 14 and her last day as prime minister will be on February 7.

"I am not leaving because it was hard. Had that been the case I probably would have departed two months into the job. I am leaving because with such a privileged role, comes responsibility, the responsibility to know when you are the right person to lead, and also, when you are not," she said.

"I know what this job takes, and I know that I no longer have enough in the tank to do it justice. It is that simple," she said.

Ardern faced a tough election campaign this year. 

Her party won reelection two years ago in a landslide of historic proportions, but recent polls have put her party behind its conservative rivals.

Ardern said she still believed Labour would win the election.