Former prime minister Helen Clark has lost ground in the race to become the next United Nations secretary-general, still seventh of the nine candidates but picking up discouraging votes.

LISTEN ABOVE: UN correspondent for the Huffington Post Evelyn Leopold spoke to Rachel Smalley 

Former Portuguese Prime Minister Antonio Guterres continues to lead the pack, with 12 encourage, two discourage and one no opinion.

Earlier this month Miss Clark earned six encourage votes, seven discourage and two no opinions, however at the fifth UN Security Council secret ballot on Monday in New York she she tallied six encourage votes and nine discourage.

Guterres, who was prime minister of Portugal from 1995 to 2002 and served as United Nations High Commissioner for Refugees from June 2005 to December 2015, also won the first four rounds of secret balloting by the Security Council.

Former Serbian Foreign Minister Vuk Jeremic came in second while Slovakia's Foreign Minister Miroslav Lajcak was third.

Miss Clark has placed between sixth and eighth in previous voting rounds.

The Security Council will hold secret ballots until a consensus is reached on a candidate to replace UN chief Ban Ki-moon of South Korea, who steps down at the end of 2016 after serving two five-year terms.

The council will hold the next secret ballot on October 5, Russian UN Ambassador Vitaly Churkin said.

He said during that vote, the ballots cast by the five veto powers - the United States, France, Britain, China and Russia - would be a different colour from the votes of the remaining 10 council members, though they remain anonymous.

This allows candidates to see if they could be facing a veto.

UN correspondent for the Huffington Post Evelyn Leopold told Rachel Smalley she doubts the former Prime Minister will move up the list when veto powers are exercised, because Clark's not from Eastern Europe and she's considered an Anglo.  

However, Miss Clark says she'll keep campaigning and is looking forward to the next stage.

She tweeted after the result, thanking Security Council members who supported her.

Many thanks to UN Security Council Members who continued to support me as #NextSG. Continuing campaign &looking 4ward 2 next phase #Helen4SG

— Helen Clark (@Helen4SG) September 26, 2016