Former New Zealand Prime Minister Helen Clark will be appointed to head the United Nations Development Programme, according to local media yesterday.

New Zealand political leaders would not confirm the appointment, which is expected to be announced by UN Secretary General Ban Ki-Moon.

Ms Clark led the government for nine years before being defeated by John Key's centre-right National Party in an election in November last year.

She had been reported to be a front runner to head UNDP, which is responsible for the UN's global development work with a budget of about €3.7 billion.

Mr Key's government has been lobbying for Clark's appointment and the Prime Minister said yesterday that her appointment would be a tremendous honour for New Zealand.

"She has the skills, the confidence, the capability to do the job - and that would be great for New Zealand and for the UNDP," said Ms Clark's successor as leader of the Labour Party, Phil Goff.

Ms Clark was in New Zealand's Parliament for more than 27 years and restored unity to a divided Labour Party after taking over the leadership in 1993.

She proved to be a strong manager of the country from 1999, although her sometimes-dour style saw her first administration dubbed Helengrad.

She would have become Labour's longest-serving Prime Minister if she had been able to hold on to power until August this year.