Watch live: Jacinda Ardern on oil and gas, Obama visit, Indonesian President

Obama has been brought to New Zealand by the NZ-US Council to promote the relationship between the two countries which was icy for many years over New Zealand's anti-nuclear policy.

Prime Minister Jacinda Ardern is expected to address the future of oil and gas exploration, visiting Indonesian President Joko Widodo, the upcoming visit of Barack Obama, and possible changes to the Crimes Act in her post-cabinet press conference at 4pm.

Ardern surprised petitioners at Parliament today when she turned up to accept a Greenpeace petition, signed by 45,000 people, to end oil and gas exploration in New Zealand.

She told the crowd that she wanted to take more time before making a decision on the issue.

Also on the agenda is the current visit by Indonesian President Joko Widodo, and the visit later this week by former US President Barack Obama.

She may also make an announcement after Cabinet discusses the 'year and a day' section in the Crimes Act.

Section 162 of the Crimes Act says that no one is criminally responsible for the killing of another, unless the death takes place within a year and a day after the cause of death.

Crown Law cited the rule as an obstacle to prosecution in the CTV building case, where 115 people died when the building collapsed in the 2011 earthquake.

Police last year decided not to prosecute because they did not believe a prosecution would succeed.

Ardern met with the victims' families last month and said afterwards that she believed the rule had no place in New Zealand law.