"We are referring to all countries: we're saying please no push backs at this stage, this is a time to show your humanitarian spirit and generosity towards people who are going through some severe trauma," said Melissa Fleming, spokeswoman for the UN High Commissioner for Refugees (UNHCR).
Fleming later told AFP that no mass refugee flows from Libya had been detected so far but that close contact was being kept with authorities in border countries such as Tunisia.
"At this time it's just contingencies and assumptions that when there is violence and human rights abused there will be people fleeing," she explained.
The UNHCR also expressed concern about the dangers for at least 11,000 African, Iraqi and Palestinian asylum seekers heading to Europe who were hosted by Libya.
"We ask that neighbouring countries respond to possible arrivals from Libya in a humanitarian manner," Fleming told journalists, adding in response to a question about Italy that the appeal included "all countries".
Italian officials say a pact with Libya on immigration has reduced undocumented arrivals of boat people from Africa by more than 90 percent. Libya has threatened to lift controls if Europe tries to topple Muamar Kadhafi.
Since the separate unrest in Tunisia, the Italian island of Lampedusa, a first port of call for those fleeing across the Mediterranean, has experienced a sharp increase in arrivals of Tunisians attempting to reach the European Union.
Before the revolt against the Kadhafi regime, the UNHCR had registered more than 8,000 refugees from Africa and the Middle East inside Libya and had 3,000 more asylum cases pending.
The agency's staffs in the country has had little direct contact with them since a dispute over the UNHCR's presence led to restrictions on their work last year.
"A journalist has passed on information to us from Somalis in Tripoli who say they are being hunted on suspicion of being mercenaries," said Fleming.
"He says they feel trapped and are frightened to go out, even though there is little or no food at home," she added.