Watch live: Acting Prime Minister Winston Peters press conference

Cabinet has discussed the spike in the number of deaths from synthetic cannabis use.

Acting Prime Minister Winston Peters spoke about the need to turn around the numbers at his weekly post-Cabinet press conference. He said urgent action would be required.

Agencies would look at what action could be taken to address the problem, Peters said.

Peters reiterated the need for a referendum on the legalisation of cannabis for personal use.

Users should know what they are taking so they were not taking dangerous substances, Peters said.

Prime Minister Jacinda Ardern will return to Wellington with her partner and daughter on Saturday and set up home at Premier House in readiness for her return to the top job on Monday.

Peters outlined some of the big events he had overseen in the six weeks he had been acting PM, including announcing changes to Working for Families and the purchase of new air force planes.

Peters is hosting his last weekly post-Cabinet press conference in the role before Ardern returns to work.

Peters is due to leave the country on Thursday and told Q+A that Ardern would take over as Prime Minister from that moment rather than next Monday.

Ardern has been at home with baby Neve since Neve was born about six weeks ago but is set to return to Parliament next week.

Ardern released a Facebook video on Sunday saying she expected to hit the ground running and would make an employment related announcement in her first full week back.

Peters could also face questions on the criticism of him at the National Party conference, including from National Party President Peter Goodfellow, who said National had "dodged a whisky-swilling, cigarette-smoking, double-breasted and irrational bullet" after Peters opted to side with Labour.

It came after Peters had predicted National Party leader Simon Bridges would not last until the election and "the jackals" would take out National's deputy leader Paula Bennett.