US secretary of state Hillary Clinton stepped up Western calls on Libyan leader Muammar Gaddafi to quit, brushing off his threat to attack Europeans in their homes and offices.
"Instead of issuing threats, Gaddafi should put the well-being and the interests of his own people first and he should step down from power and help facilitate a democratic transition," Clinton told reporters on a trip to Spain.
In an address relayed to some 100,000 supporters in Tripoli's Green Square on Friday, Gaddafi urged Nato to halt its bombing campaign or risk seeing Libyan fighters descend on Europe "like a swarm of locusts or bees".
"Retreat, you have no chance of beating this brave people," Gaddafi said. "They can attack your homes, your offices and your families, which will become military targets just as you have transformed our offices, headquarters, houses and children into what you regard as legitimate military targets," he said.
NATO announced it had stepped up strikes on Gaddafi forces in west Libya including the capital Tripoli, saying it had carried out more than 50 attacks since Monday.
Spanish Foreign Minister Trinidad Jimenez said the alliance stance was unchanged.
"Spain's and the international coalition's response is to maintain the unity and determination with which we have been working these past months," she said.
Libyan rebels who had advanced to within 80 km (50 miles) of the capital were stopped in their tracks on Friday by a barrage of rocket fire from government forces, underlining the dogged resistance of Gaddafi troops to a five-month revolt.
"(It) was obviously a strategic withdrawal because of the battlefield situation and the amount of bombardment that the revolutionary forces were receiving," said rebel spokesman Ahmed Bani.