The United Nations is exploring ways to re-enter Tripoli as soon as possible, a spokesperson for the world body said Monday, following the announcement that 12 international staff left owing to unrest in parts of the Libyan capital.

According to media reports, angry mobs attacked a UN office in Tripoli on Sunday after NATO bombed Colonel Muammar Al-Qaddafi's family compound in an attack that reportedly killed one of the Libyan leader's sons and several grandchildren.

NATO forces have been carrying out air strikes in response to a Security Council resolution adopted in March that authorized UN Member States to take "all necessary measures" to protect civilians in Libya, where initially peaceful protests have transformed into open conflict between opposition groups and the Qaddafi regime.

The conflict has created a humanitarian crisis in the country, while an estimated 665,000 people, including large numbers of third-country nationals, have fled to neighboring countries.

The UN said that humanitarian operations are still being carried out and there are still international staff members in the rebel-held city of Benghazi. It hopes to return to the capital as soon as the situation allows.

"Humanitarian operations are continuing, with the redeployed staff from Tripoli supporting operations in western Libya from Tunisia," UN spokesperson Martin Nesirky told reporters in New York.

Meanwhile, the UN Office for the Coordination of Humanitarian Affairs (OCHA) reports that, as of yesterday, more than 12,000 people had been evacuated from the besieged city of Misrata. It also remains concerned that deaths and injuries continue to be reported from the fighting there.

UN officials have stressed the need for medical supplies and staff, while also warning that stocks of food and water are sufficient for only one to two months in some areas of the country.

The protests that began in Libya in February are part of a broader pro-democracy movement across North Africa and the Middle East that has led to the downfall of long-standing regimes in Tunisia and Egypt.