An illegal seven-storey residential building on the outskirts of India's business capital Mumbai has collapsed, killing at least 29 people and injuring dozens of others.

The dead include nine children and seven women, according to initial reports.

Rescue workers are struggling to pull the injured out of the debris. Nearly 100 police personnel and emergency workers are engaged in the rescue operation.

The death toll is likely to increase as some of the injured are said to be in a critical condition.

Officials suspect that the use of poor construction materials could have caused the collapse. Many of the floors are reported to have been built in just three to four months.

The apartment block in suburban Thane was being built without official licences, government officials say.

"This building had no occupation certificate. It does not have an architect or a structural consultant. The building came up in one and a half months. So naturally the construction will be poor. It is difficult to say who is responsible. But we all are," Maharashtra Labour Minister Ganesh Naik said.

A case has already been registered against the builder, who remained untraceable after the disaster.

Although the building was still under construction, people started occupying the lower floors compounding the tragedy.