* Owner of collapsed building on run, border authorities alerted
* Angry workers protest in Dhaka, burning and smashing cars
* Seven pulled from rubble alive, 72 hours after disaster
* Rescuers work frantically to save 15 trapped workers
Two factory bosses were arrested in Bangladesh on Saturday, 72 hours after the deadly collapse of a building where low-cost garments were made for Western brands, as the death toll rose to 325 and angry workers protested on the streets of the capital.
The owner of the eight-storey building that fell like a pack of cards around more than 3,000 workers was still on the run.
Police said two of his relatives had been detained to compel him to hand himself in, and an alert had gone out to airport and border authorities to prevent him from fleeing the country.
Officials said the Rana Plaza, on the outskirts of the capital, Dhaka, had been built illegally without the correct permits, and the workers were allowed in on Wednesday despite warnings the previous day that it was structurally unsafe.
The owner and managing director of the largest of the five factories in the complex, New Wave Style, surrendered to the country's garment industry association during the night and they were handed over to police.
The factory, which listed many European and North American retailers as its customers, occupied upper floors of the building that officials said had been added illegally.
"Everyone involved - including the designer, engineer, and builders - will be arrested for putting up this defective building," junior internal affairs minister Shamsul Huq told reporters.
Anger over the working conditions of Bangladesh's 3.6 million garment workers - most of whom are women - has grown since the disaster, triggering protests and clashes with police. Hundreds were on the streets again on Saturday morning, smashing and burning cars.
Miraculously, people were still being pulled alive from the rubble, seven in all since daybreak on Saturday.
Frantic efforts were under way to extract 15 people trapped under the mound of broken concrete who were being supplied with dried food, bottled water and oxygen.
About 2,500 people have been rescued, at least half of them injured, from the remains of the building in the commercial suburb of Savar, about 30 km (20 miles) from Dhaka.
WRONG PERMIT, ILLEGAL FLOORS
Emdadul Islam, chief engineer of the state-run Capital Development Authority (CDA), said on Friday the owner of the building had not received the proper building consent, obtaining a permit for a five-storey building from the local municipality, which did not have the authority to grant it.
"Only CDA can give such approval," he said. "We are trying to get the original design from the municipality, but since the concerned official is in hiding we cannot get it readily."
Furthermore, another three storeys had been added illegally, he said. "Savar is not an industrial zone, and for that reason no factory can be housed in Rana Plaza," Islam told Reuters.
Dhaka District police chief Habibur Rahman identified the owner of the Rana Plaza building as Mohammed Sohel Rana, a leader of the ruling Awami League's youth front.
"People are asking for his head, which is quite natural. This time we are not going to spare anybody," said H.T. Imam, an adviser to the prime minister.
Wednesday's collapse was the third major industrial incident in five months in Bangladesh, the second-largest exporter of garments in the world. In November, a fire at the Tazreen Fashion factory on the outskirts of Dhaka killed 112 people.
Such incidents have raised serious questions about worker safety and low wages, and could taint the reputation of the poor South Asian country, which relies on garments for 80 percent of its exports.
Sixty percent of Bangladesh's garment exports go to Europe. The United States takes 23 percent and Canada takes 5 percent.
North American and European chains, including British retailer Primark and Canada's Loblaw, said they were supplied by factories in the Rana Plaza building.