LOS ANGELES-Amazon has pledged to investigate allegations that hundreds of teenagers are working illegal hours at a Chinese factory producing its Echo devices.

A new report by China Labor Watch claims more than 1,500 “interns” were manufacturing the smart assistants at a factory run by supplier Foxconn.

The teenagers, aged between 16 and 18, were reportedly pressured into work 60 hours a week and night shifts.

Foxconn has blamed local managers and vowed to improve monitoring of staff. The company, which makes products for a number of technology giants, has allegedly fired two senior staff members at the site in Hengyang, Bloomberg reports.

It is the latest in a string of controversies surrounding working conditions at the manufacturer, which is headquartered in Taiwan.

In 2017, it emerged some students were working illegal overtime at another Foxconn facility making Apple iPhone Xs.

What does the report say?

The latest report into Foxconn, first detailed in the Guardian, alleges hundreds of school students have been drafted in from local vocational schools to help fulfil orders.

China Labor Watch say many students sleep in shared dormitories and face pressure from teachers, who are also recruited, to work hours that violate labour regulation.

“If interns were unwilling to work overtime or night shifts, the factory would arrange for teachers to pressure workers,” the report says. “For interns who refuse to work overtime and night shifts, the factory requests teachers from their schools to fire them.”

Activists also make allegations of physical and verbal abuse by teachers at the site. The intern’s schools are compensated financially for their time, the report adds.