A New Zealand nurse was abducted by the Islamic State group five years ago and is now missing, the Red Cross has revealed in a plea for help in finding her.
But New Zealand's government says she should not have been publicly named.
Louisa Akavi, now 62, was kidnapped in October 2013 by armed men in Syria while doing humanitarian work for the Red Cross and is thought to have been held by ISIS since.
With victory declared over ISIS in Syria weeks ago, her whereabouts is still unknown.
The International Committee of the Red Cross on Monday broke a long-standing silence to make an appeal for information that could help find her and two others - Syrian drivers Alaa Rajab and Nabil Bakdounes.
The trio were travelling in a convoy delivering medical supplies in northern Syria when they were stopped by armed men. Four others who were abducted were released the following day.
The last credible sighting of Akavi was in December, and she was described as working in a clinic in the village of Sousa, one of the final remaining areas that had been held by ISIS.
'What we actually know is that Louisa has been working as a nurse during her abduction which shows her dedication and commitment,' ICRC director of operations, Dominik Stillhart, said.
The organisation says there's now fear of losing track of her following the fall of ISIS.
'Though, we remain hopeful this period will instead open new opportunities for us to learn more about her whereabouts and wellbeing,' ICRC said.
Since 2014, New Zealand media outlets and some international news organisations have had an agreement with the New Zealand government and the Red Cross to not make Akavi's abduction public, with fears it could put her life in jeopardy.
The charity on Monday said that with the fall of ISIS, they felt they were 'extremely close' to finding Akavi and the time was right to speak out.
But Prime Minister Jacinda Ardern on Monday lamented that Akavi had been publicly identified, because of the risk.
'It remains the government's view that it would be preferable if this case were not in the public domain,' she said, declining to answer a lengthy series of questions on the matter.
Stillhart later told reporters he was 'slightly surprised' by Ardern's comments and that the Red Cross had been given government backing.
'Every decision, ever since October 2013, was to maximise the chance of winning Louisa's freedom and every decision was coordinated with the New Zealand government,' he said.
A spokesman for the prime minister said officials had never endorsed the plan.
Foreign Minister Winston Peters said the government was still operating on the basis Akavi was alive, and had during the five-year period continuously worked to find her, including by deploying a non-combat Defence Force team to Iraq to search in Syria.
'The New Zealand government continues to work tirelessly to locate her and bring her to safety,' he said.
The missing trio have been held longer than anyone in Red Cross history.
The organisation said a series of ransom offers had been made by ISIS for Akavi's release, including one of 20 million euros ($A32 million).
New Zealand's government and the Red Cross both say they have policies of not paying ransoms.
Akavi has spent more than three decades with the organisation and taken part in 17 missions, including in Iraq, Afghanistan, Bosnia and Chechnya, where she survived a deadly attack on a Red Cross hospital in 1996.
A spokesman for Akavi's family, Tuaine Robati, said they were incredibly proud of her work and simply wanted her home.
'We think about her every day and hope she feels that and finds strength in that.'