United Nations, Jan 20 (IANS): Tens of millions of US dollars more might be needed to salvage the Safer oil tanker off Yemen's Red Sea coast, a United Nations spokesman said.

"What we have been told is that the increase in cost for a very large crude (carrier) is more than 50 per cent of the original cost," Farhan Haq, Deputy Spokesman for UN Secretary-General Antonio Guterres, told a press briefing, on Thursday.

He said the additional cost is around 20 million dollars, noting "that's a rough figure".

"We are trying and we are also seeking some support from other contributors to get the funds needed," he added.

The Safer, currently carrying more than 1 million barrels of oil, has been moored off the port of Hodeidah since 1988 as a crude oil storage and offloading platform, Xinhua news agency reported.

The UN has warned that the decaying tanker is an environmental and humanitarian threat.

Earlier this week, Haq told reporters that donors have pledged more than $84 million of the funding required for the UN-coordinated plan to prevent a major oil spill from the Safer, with more funding from the private sector expected soon.

He pointed out that the key challenge for the emergency operation of transferring oil from the decaying tanker to a safe vessel to begin is procurement of a very large crude carrier to take on the oil.

"The UN is working expeditiously with a maritime broker and other partners to find a workable solution and remains confident the work can begin in the coming months," said Haq.