Tripoli, Libya (CNN) -- About 200,000 Libyans remain under threat as Moammar Gadhafi loyalists battle to the end in the only two areas still contested in Libya: Bani Walid and Sirte, the coastal birthplace of the fallen leader.
Fierce fighting yielded a path into Sirte's port Tuesday for revolutionary fighters, approaching the besieged city first from the south, then the west. With supply routes largely severed, water, food and medicine are in short supply, said Col. Roland Lavoie, military spokesman for NATO.
He said the shortages and a lack of electricity have placed enormous pressure on the civilian population, who are also being used as human shields by Gadhafi loyalists. One of their staging areas has been the main hospital in Sirte, where Gadhafi's fighters feel protected from NATO airstrikes.
Control over the strategically important Sirte port has changed hands before -- anti-Gadhafi fighters have previously taken the port during the day and retreated at night.
"We consider it contested," Lavoie said about Sirte. "So it means that a big part of the town is controlled by Gadhafi forces."
He said National Transitional Council forces have made significant gains in Sirte over the last three days but it would be "premature to go farther than that" in making an assessment.
Meanwhile, in the eastern city of Benghazi, transitional council members were meeting for a third day to discuss forming a government.
Council members previously agreed the government should include a premier, a vice premier and 22 ministers.
But an announcement of the new government's creation should be contingent on wresting control of all cities from forces loyal to Gadhafi, said senior council member Abdulrazag Elaradi.
The meetings began Sunday, and the formation of a government could take up to a week.
The council said it will expand as cities are liberated to ensure representation in all regions of the country.
The council announced Saturday that it had advanced into Sirte following 24 hours of NATO aerial bombardments.
"Among the reports emerging from Sirte are executions, hostage-taking and the calculated targeting of individuals, families, and communities within the city," NATO has said. The organization has also pointed to mercenaries employed by the pro-Gadhafi side and civilians denied access to critical food, water and medical care.
The battle for Sirte has been difficult because Gadhafi loyalists have been using snipers and advanced weapons such as machine guns, according to the revolutionary fighters.
CNN's Mohammed Tawfeeq and Tommy Evans contributed to this report.