Please translate this from english to bengali The death toll from the collapse of a Bangladesh factory building has passed 500, officials said, as police investigating the disaster arrested an engineer who warned the day before the tragedy that the eight-storey complex was unsafe. The detention of Abdur Razzak brought to nine the number of people held over the disaster, which has put the spotlight on the many western clothing retailers using the country as a source of cheap goods. Scores of relatives remained at the site in a Dhaka suburb on Friday, clutching photographs of loved ones attesting to the many more still missing, as the number of deaths in the country's worst industrial accident rose to 501. Razzak had been called to Rana Plaza in Savar, 20 miles north of the capital, by its owner when cracks appeared in concrete pillars the day before the accident. Despite his warning that the building was unsafe – quoted in local media hours before it came crashing to the ground – thousands of mostly female workers were sent back into its upper-storey factories when the morning shift began the next day. Police said Razzak had been arrested because he had been involved in the construction of the building. Duty-free access offered by western countries and low wages have helped turn Bangladesh's garment exports into a $19bn (£12bn) a year industry, with 60% of clothes transported to Europe.