* Rebel says 32 Gaddafi troops defect in mutiny
* Crack Khamis Brigade slowed down on edge of Misrata
* For more on uprisings, click on [nTOPMEAST] [nLDE71O2CH]
(Updates number of defections, adds background)
By Mariam Karouny
RAS JDIR, Tunisia, March 12 (Reuters) - A crack Libyan brigade commanded by Muammar Gaddafi's son Khamis was slowed by a mutiny as it advanced on Misrata on Saturday, with 32 soldiers joining the rebels holding the city, a rebel there said. One defector was a general, said the rebel named Mohammed. The feared 32nd Brigade tried but failed earlier in the day to take Misrata, the last major rebel holdout in western Libya.
Stalled about 10-15 km south of the city, the brigade broke out in a fire-fight after dozens of troops balked at the idea of killing innocent civilians in the impending attack, rebel spokesman Gamal added.
"Exactly 32 (soldiers) joined the rebels today," Mohammed said. "They have been interrogated by the rebels."
The events could not be confirmed independently. Journalists have been prevented from reaching the city by the authorities.
Other government forces continued their push eastward, and officials took foreign journalists from Tripoli to the eastern oil town of Ras Lanuf to prove the government controlled it.
Rebel spokesman Gamal said by telephone from Misrata: "In the morning, there was a gathering of pro-Gaddafi forces with the apparent aim of attacking the city but God protected this city. There was dissent within the Khamis Brigade.
"We knew from soldiers who defected after the dispute. They joined the rebels and said that dozens of the battalion members expressed reluctance to kill innocent civilians.
"Some of them ran away. More would have joined us but they were shot by the pro-Gaddafi men."
On Thursday, government forces recaptured the city of Zawiyah, 50 km (30 miles) west of Tripoli -- the only other town in western Libya which openly defied Gaddafi's four-decade rule.
Misrata residents and rebels said government troops had tried to fight their way into the city earlier in the day.
One rebel, Mohamad Ahmed, said he could hear the sound of anti-aircraft guns getting closer to the city centre.
Misrata -- around 200 km (130 miles) east of Tripoli -- is Libya's third largest city and an important commercial hub with a population of about 300,000.
The government says the rebels are bandits or al Qaeda operatives. Gaddafi's opponents deny any link to religious militants, saying they are fighting for democratic change.
Rebels and residents in Misrata had been preparing for a government onslaught since troops regained control of Zawiyah.
Mussa Ibrahim, a government spokesman in Tripoli, could neither confirm nor deny a military operation was under way in Misrata.
"We want to give people a chance to lay down their arms. There is a hard core of al Qaeda fighters there. It looks like a Zawiyah scenario," he said.
"Some people will give up, some will disappear, so their numbers are declining. Tribal leaders are talking to them. Those who stay behind, we will deal with them accordingly. Misrata will be completely within united Libya very soon". Others in Misrata said the besieged city, much like Zawiyah in the last days before its fall, was running out of medicine.
"What worries us the most about the humanitarian situation is the lack of medicines and care facilities," said the rebel Mohammed.
Rebel spokesman Gemal said: "There is a lack of medicine and medical equipment. There is no way for the city to replenish the stock ... There is no shortage of food, praise to Allah." (Reporting by Souhail Karam in Rabat, Tarek Amara in Tunis, and Maria Golovnina in Tripoli; Writing by Maria Golovnina and Tom Heneghan; editing by Tim Pearce)