Nepal, which has 245 troops protecting the UN mission in Iraq, will soon carry out a security assessment in Tripoli on the proposed deployment, said the official, who spoke on background.
Last month, the United Nations announced that its staff would be returning to Tripoli to work alongside the new UN-backed government of Prime Minister Fayez al-Sarraj.
The UN mission pulled out of the Libyan capital in July 2014, amid fierce fighting between rival militias.
Sarraj returned to Tripoli in late March but has been struggling to assert his government's control over Libya's state institutions to put an end to the chaos in Libya since the 2011 fall of Moamer Kadhafi.
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UN peacekeeping chief Herve Ladsous yesterday said his department was working on setting up a "guard unit to provide security to the UN mission when it returns to Libyan territory."
He declined to name the country that was offering troops and stressed that there were no plans to deploy a full peacekeeping force to Libya.
A peacekeeping operation would not be feasible because of "the fragility of the political process and huge security concerns about jihadist organizations and others," he said.
It remains unclear how many troops Nepal would be sending to Libya for the guard unit, which would be the third such force set up to protect UN staff working in missions.
Aside from the Nepalese guard in Iraq, Uganda has sent 430 troops to protect the UN mission in Somalia, based in Mogadishu.
UN officials suggested that the guard unit in Tripoli would be close in strength to the Mogadishu force.