They gather nightly, ready to die for the Brother Leader. Wrapped in loyalist green, waving flags, chanting slogans, holding aloft portraits of their "Guide", singing, dancing and praying, they are Muammar Gaddafi's human shields against Nato air strikes.

In the early hours of Friday morning, exactly 25 years after US forces bombed Gaddafi's Bab al-Aziziya compound in central Tripoli, thousands gathered in defiance of the new international coalition against the Libyan regime's brutal efforts to suppress the uprising from the east.

Whipped up by loyalist chants led from loudspeakers and patriotic songs, they were already in a state of fervour when Aisha Gaddafi, the Libyan leader's daughter, appeared high in the skeleton of a bombed-out building.

Against a backdrop of the shattered facade and draped in a flowing headscarf of green and gold, Aisha pumped her fists at the crowd as they roared and ululated their approval.

Just a few hours earlier, Nato warplanes had flown sorties over Tripoli. Explosions and responding gunfire and anti-aircraft fire echoed around the capital, destroying at least one military site and causing blast damage to a nearby university cafeteria.

Aisha's message was one of uncompromising defiance. Referring to the strike in 1986, she said: "They rained down on us their missiles and bombs, they tried to kill me and they killed dozens of children in Libya. Now a quarter of a century later the same missiles and bombs are raining down on the heads of my and your children."

Below her was a statue of a giant golden fist crushing a western war plane in its grip. The throbbing crowd – mainly men, but including hundreds of women separated to one side – appeared intoxicated on love and loyalty.

"Talk about Gaddafi stepping down is an insult to all Libyans because Gaddafi is not in Libya, but in the hearts of all Libyans," Aisha told them. "Gaddafi said if the Libyan people don't want me I don't deserve to live. The Libyan people responded, 'He who doesn't want you does not deserve life'."

Half a dozen of Gaddafi's fabled female protection guards stood to the side as Aisha spoke, some with their faces covered, amid an atmosphere akin to a hyped-up football crowd crossed with a rock concert.

The cult of Gaddafi is evident across the capital. Huge portraits of him – saluting with a stern expression, beaming with his hands clasped, silhouetted against the rays of a rising sun – hang from buildings. Many in the crowd on Friday night wore miniature laminated versions on green ribbons around their necks.

"I love him more than my husband," said Randa Mohamed, 28, her voice hoarse from shouting and chanting. "We will never leave him. I will do anything to protect him."

This overt display of loyalty fractures when rare opportunities for rushed conversations out of earshot of the ubiquitous regime minders and informants arise. "He must go for the sake of Libya," is a view expressed in whispers. These few glimpses beneath the surface are always accompanied by visible fear at the possibility of being overheard and punished.

But in the Bab al-Aziziya compound, there was only one message: devotion to Gaddafi and hatred of Nato and Libya's rebel opposition. "We will never give up. Victorious or we die," ran one chant.

As the foreign media were escorted from the compound at the end of Aisha's speech, the "Zenga Zenga" song blared from speakers. The words are taken from a speech by Saif al-Islam, Aisha's brother and Gaddafi's son, early in the conflict, in which he pledged to hunt down the rebels.

"House to house, room to room, alley to alley, person to person we will disinfect the whole country from filth," it goes. "Zenga Zenga" – alley to alley – has now become part of loyalist Libya's lexicon, a chilling term of approval among people in Gaddafi's grip.