* Plant was being restarted after Eid holiday
* Owners say boiler had been working before explosion
* Company supplies clients in Europe, including Littlewoods
* Lindex says firm was one of its most important suppliers (Adds quotes from firms, details)
DHAKA, July 4 (Reuters) - A boiler explosion at a Bangladeshi garment factory killed 10 people and injured dozens, fire officials said on Tuesday, the latest accident to hit one of the world's biggest garment producers.
The incident late on Monday happened during maintenance work at the factory owned by Multifabs Limited, a Bangladeshi company on the outskirts of the capital, Dhaka, company and fire brigade officials said.
"Nine people were killed in the blast and one died in hospital," fire service official Palash Chandra Modak said.
The firm supplies knitted apparel to clients in Sweden, Denmark, Germany, Russia, Spain, Netherlands and Britain, including to Littlewoods, one of Britain's oldest retail brands, according to its website.
Fashion chain Lindex, which is part of Finnish retailer Stockmann, said the Bangladeshi firm was one of its most important suppliers.
Multifabs said the six-year-old boiler, procured from Germany, had just been serviced. The blast happened as the factory was being readied to resume operations following a 10-day shutdown for the Eid holiday marking the end of the Muslim holy month of Ramadan.
"This was an accident. Everything was fine," Mahiuddin Faruqui, the company's chairman and managing director, told Reuters. "The boiler was running well. After servicing when workers were trying to restart it, it went off."
Bangladesh's garment-making industry, the biggest in the world after China's, employs 4 million people and generates 80 percent of the country's export earnings.
For years, activists had criticised retailers for failing to improve working conditions in supply chains characterised by long hours, low pay, poor safety standards and a lack of union representation for workers.
But Bangladesh came under close scrutiny after the collapse of the Rana Plaza factory complex in 2013, which killed more than 1,100 people, and a fire at a garment factory in 2012 that killed 112 workers.
It sparked demands for greater safety and put the onus to act on foreign companies sourcing clothing from Bangladesh.
Two international coalitions were formed to help fund improvements to building and fire safety at thousands of garment factories across Bangladesh.
One of those, the Alliance for Bangladesh Worker Safety, said fire incidents in Bangladeshi factories fell to 30 in 2015 from 250 in 2012. The alliance represents most North American importers of readymade garments, including Canadian Tire Corp , Gap Inc, Sears Holdings Corp, Target Corp and Wal-Mart Stores.
Multifabs, which started operating in 1992, generated exports of $70 million in 2016, mostly from sales to Europe.
Its major buyers were fashion chain Lindex, Aldi of Germany and Rexholm of Denmark, Faruqui said.
Stockmann Communications Manager Anna Bjarland confirmed that the factory supplied garments to both Stockmann and Lindex.
Bjarland said the company was investigating and was waiting for more information from the Bangladeshi authorities and their local sales office.
Stockmann is a member of the industry group Business Social Compliance Initiative (BSCI), and Bjarland said that Multifabs had cleared a BSCI audit in May 2016, valid for two years.
Lindex said in a separate email that the Bangladeshi firm was one of its most important suppliers.
The Multifabs factory hit by the blast produced 100,000 pieces of garment a day, generating around $6 million in revenue a month, factory and operations director Mesba Faruqui told Reuters.
He said the boiler had been working for about an hour when it exploded.
"We are surprised and saddened ... every year around twice or thrice the boiler is serviced by our men and men from Germany," he said.
Bangladesh's chief boiler inspector Mohammad Abdul Mannan said his department had inspected the Multifabs' boiler a year ago and that the next inspection had been due this month.
Sulav Chowdhury, chief executive officer of the Bangladesh Knitwear Manufacturers and Exporters Association, of which Multifabs is a member, said the industry had gone through a "huge shift" since the Rana Plaza disaster.
"There has been structural change, and we have worked hard for it," he said. "So I would say this is a stray incident." (Additional reporting by Serajul Quadir in DHAKA, Krishna N. Das in NEW DELHI, Promit Mukherjee, Abhirup Roy, Zeba Siddique and Euan Rocha in MUMBAI; Tuomas Forsell in HELSINKI; Writing by Sanjeev Miglani; Editing by Paul Tait and Neil Fullick)