Having no access to the western part of Libya, the UN has expressed concern about the plight of the people who were being prevented from leaving the country.
The majority of the 172,000 people who have fled, mainly to bordering nations of Tunisia and Egypt, are male migrant workers.
Valerie Amos, the UN emergency relief coordinator, said that "unverified reports" suggested that people inside the country "are being prevented from leaving". On Thursday, there was a sharp drop in the number of people leaving Libya.
"We hope that free movement of people can continue", Amos said, adding that reports suggested the borders on the Libyan side were being guarded by pro government forces. Amos will launch a fresh appeal on Monday to help the thousands of people who have now crossed the Libyan borders and are waiting to be evacuated back to their home countries.
Amos said that the world body had "scaled up" its efforts on both sides of the border during the past three days to quickly process those fleeing from inside Libya.
A basic camp had been set up on the Tunisian side of the border where hot meals are being served. Amos called on countries to keep their borders open for those fleeing from strife torn Libya, as rebel groups clashed with forces loyal to Muammar Gaddafi, demanding an end to his 41 year rule.
Meanwhile, UN has received a letter from Libya requesting that diplomatic credentials for ambassador Mohamed Shalgham and deputy ambassador Ibrahim Dabbashi be no longer recognized. Both men, and the rest of the staff at Libya's UN mission, have publicly renounced Gaddafi for a violent crackdown by government forces on protesters seeking his ouster.
Nesirky noted that Libya remains a recognized UN member state and "when any country sends a letter naming the permanent representative, that person is the person who will be recognized."
Gaddafi has appointed veteran Libyan diplomat, Ali Abdussalam Treki, as the country's new ambassador, and he is expected to present his credentials to Secretary-General Ban Ki-moon.
Treki served as the president of the General Assembly during its previous session, last August, when Gaddafi gave a long rambling speech. He was also the country's foreign minister from 1977 to 1980, and later envoy to the League of Arab States in Cairo and ambassador to France.
When asked Treki's current location, Nesirky said, "No idea".