Water shortages in Tripoli are "serious" but not "critical", the United Nations' humanitarian coordinator in Libya said Friday, dismissing fears of a looming disaster.

Panos Moumtzis said providing water to four million people in Tripoli and across a swathe of Libya remained "the most important and urgent and immediate priority" for aid agencies, but the situation was in hand.

Residents of the capital have been without running water for close to a week as the war forced disruptions to Libya's state-of-the-art system that draws water from underground wells deep in the south of the country.

"The situation at the moment with the provision of water remains serious but I want to clarify that it is not critical," Moumtzis said.

The United Nations and other international actors say they are importing about 11 million litres of drinking water to stave off an emergency, while engineers race to get the system back on line.

With over 580 wells linked to the Great Man Made River system no longer feeding the city, Tripoli residents have tapped long-dormant boreholes to procure water for everyday use while bottling companies provide free drinking water.

"Quite an adequate response has been provided so far", Moumtzis said.

Members of the National Transitional Council said Friday they hoped the water shortage would only be a matter of days and residents would cope.

"It is not a major problem, it is a problem, but people are dealing with it," said Alamin Belhaj, an NTC member from Tripoli.

He said that Tripoli's citizens would tolerate the inconvenience, in part because fears of widespread bloodshed and a siege of the city were not realised.

"The worst case scenario was much much worse than this, so people will deal with it," said Belhaj.

But that does not mean life is easy for the millions who live in the city and western Mediterranean coast.

"There is a huge shortage of fuel," said the UN humanitarian coordinator, adding that Libya's interim government had requested an exception from UN sanctions in order to buy 250 metric tonnes of fuel.

"We are very concerned about the delivery of fuel in particular for humanitarian needs the lack of fuel is having a significant impact on everyday life," said Moumtzis.

The shortfall has effected the movement of everything from the offloading of ships to ambulances services he said.