More than 120 children working at an illegal embroidery factory in Delhi, India were rescued in a massive joint operation by police and social workers on Friday.

New Delhi-based organization Global March Against Child Labour reported the boys, aged between 8 and 14, were found working in dingy, cramped rooms with no light or ventilation.

"These small rooms were homes as well as workplaces for children trafficked from the states of West Bengal, Bihar and Jharkhand," the organization reported in a written statement.

According to the Press Trust of India news agency, the children were forced to work up to 16 hours a day.

One 14-year-old boy told reporters he was being paid a little over $2 US a week for 12 hours of work a day.

A Delhi lawyer involved in the case said the whole factory was illegal, and the children were essentially working as slaves.

"The whole factory is illegal. They do not have a contract with the owner and because there is no contract, they are, as it is, working as a slave," said a Delhi lawyer identified as Bhuvan.

It's a familiar problem in India's cities.

In Delhi alone, authorities believe there are 50,000 children working in factories similar to this one.

The raid, supported by the police, administration and judiciary, was conducted as part of an ongoing campaign to free Delhi of illegal child labour.

"We will take their statements, (to find out) where do they belong, how long they have been working? When everything is there, then we will take them to the children's home, then we will inform their parents," said Sonika Singh, Delhi government official.

While the raids are an effort to eradicate the problem, it will be difficult.

According to British-based aid agency Oxfam, India has the largest number of children under the age of 15 in work in the world. Some estimates put the figure at 100 million children.

While international agencies are pressuring the Indian government to crack down, there is little chance the owner of the factory, who managed to escape, will be prosecuted when caught.

With a report from CTV's Tom Kennedy