Tripoli, Libya (CNN) -- Forces loyal to Moammar Gadhafi are creating a humanitarian disaster in Bani Walid, the National Transitional Council's military spokesman charged Monday.
Col. Ahmed Bani told reporters that Gadhafi forces are robbing food stores, leaving civilian residents to starve. He also charged that Gadhafi loyalists are shooting everyone trying to join the revolution, including men, women and children. "They are carrying out mass killings," Bani said.
"This proves they are trying to destroy the town before it is liberated," he added, calling the Gadhafi forces "criminals" and "killers."
Asked by CNN why, if there is such a humanitarian disaster, NTC forces do not immediately enter the city, the colonel said the problem is "geography." There are tactics the forces must follow to reduce casualties, he said.
Bani Walid is surrounded by anti-Gadhafi forces, he said.
Asked to comment on assertions by Gadhafi spokesman Musa Ibrahim that loyalist forces in Bani Walid had captured a group of 17 mercenaries fighting for the NTC, including some British, Qatari, French and Asians, the spokesman dismissed the claim, saying, "Don't listen to him, he's from another planet."
The rebel spokesman's remarks at a news conference came after rebel fighters suffered a sizable blow. More than 20 were killed in the northern city of Sirte on Sunday, the country's transitional government said Monday.
Another 31 fighters were injured, said Abdel Rahman Busin, an NTC spokesman.
Sirte, Gadhafi's hometown, is among a handful of pro-Gadhafi strongholds left in the country.
"The injured revolutionaries in Sirte have all been hit with RPGs (rocket-propelled grenades) fired from areas congested with civilians where Gadhafi loyalists are hiding," Adel Ghulaek, spokesman for the NTC in Misrata, said Monday. "Our men are not even firing back because they do not want to kill any innocent people. Two helicopters evacuated the injured fighters last night."
Gadhafi fighters also fired anti-aircraft weapons at one of two Turkish transport planes that was parachuting aid to civilians on Sunday, NTC spokesman Abdallah Kenshil said.
The Turkish government issued a statement saying that during a food drop mission, a C-160 plane "was fired at from land by anti-aircraft weapons. However, our plane got away from the area by increasing its altitude. Our planes, which completed their air drop mission successfully, returned first to the Benghazi airport and then back to Turkey safely."
Bani, the NTC's military spokesman, said Monday that rebel forces are close to the town of Sabha in southern Libya and took the airport and the citadel. "Our flag is waving high in both locations," he said.
East of Sabha, a ragtag stream of civilians-turned-revolutionaries encountered scant resistance as they swept through oasis towns.
A CNN crew in the region saw locals in the southern Libyan town of Winzrik rejoice.
"Raise your head high, you're a free Libyan!" chanted residents in the town suddenly freed from Gadhafi's control.
People waved the pre-Gadhafi Libyan flag as revolutionary fighters swept through the area.
"I can't explain -- the feeling is wonderful," Muhannad Zarouq said. "Many emotions -- I'm so happy. I'm so glad."
But some have doubts about the revolution in a part of the country traditionally loyal to Gadhafi.
"What happens after the men with guns move on is still unclear," university physics student Mohamed Arhuma said.
The whereabouts of Gadhafi himself also are unclear.
A man identified as Ibrahim, the Gadhafi spokesman, insisted that pro-Gadhafi forces will be victorious.
"We will defeat them in a way they never would have imagined," he said on Al Rai TV, a Syrian-based station that airs pro-Gadhafi statements. "We have God and we have millions (of followers). ... We have decided it's either victory or martyrdom."
He added, "Tell the world that our nation will not surrender to gangs and it will not give them legitimacy. We will liberate Libya and return it to its true Islamic and Arabic state."
Al Rai said the comments aired Sunday were live, but it was not clear where Ibrahim may have been as he spoke.
CNN's Ben Wedeman and Yasmin Amer contributed to this report.