Media playback is unsupported on your device Media caption Police estimate 100 people were working in the four-storey building at the time

At least 23 people have been killed in a huge fire that broke out at a packaging factory in Bangladesh.

A further 70 people are reported to have been injured in the blaze at an industrial complex in Tongi, north of the capital Dhaka.

Police said about 100 people were in the four-storey building at the time, including machine operators and guards.

The blast was caused by an explosion in the boiler room, at the start of the working day, officials say.

Firefighters are struggling to bring the blaze under control.

Local fire and civil defence chief Anis Ahamed said 20 fire trucks had worked to extinguish the fire.

Relatives have been gathering outside the local hospital for news.

One man, Wridoy Barua, said he was looking for his brother. "I haven't heard from him since this morning. There is no news of him."

Image copyright EPA Image caption Relatives face an anxious wait for news of their loved ones

Low-cost manufacturing is a mainstay of Bangladesh's economy, but a series of industrial disasters in recent years have raised concerns about safety standards, the BBC's South Asia Editor Jill McGivering reports.

Tighter controls have been introduced, but dozens of workers still die every year, she notes.

Bangladesh factories: 'About 40% have major safety issues'

Can Bangladesh safety accord bring change?

At least 13 people died in a fire at a plastics factory Dhaka last year.

In 2012, 112 workers died in a fire at a factory just outside the capital.

The country suffered an even greater tragedy in 2013 when the Rana Plaza garment complex collapsed on the outskirts of Dhaka, killing 1,135 people.