At least 13 people have been killed after an Indian naval vessel lost control and hit a passenger ferry off the coast of Mumbai, a navy spokesperson said.

"This afternoon, an #IndianNavy craft lost control while undertaking engine trials in Mumbai Harbour due to engine malfunction," the spokesperson posted on X on Wednesday.

"As a result, the boat collided with a passenger ferry which subsequently capsized. 13 fatalities have been reported so far", the spokesperson said, adding that at least 99 survivors have been rescued so far.

Local authorities, including the Indian Navy, Coast Guard, and police, mobilised resources to conduct search and rescue operations.

According to local media, four helicopters were deployed to assist in the efforts.

Indian Prime Minister Narendra Modi expressed his condolences to the bereaved families and wished the injured a speedy recovery.

Prime Minister Narendra Modi said, "The boat mishap in Mumbai is saddening. Condolences to the bereaved families. I pray that the injured recover soon."

Maharashtra Chief Minister Devendra Fadnavis announced financial aid of five lakh Indian rupees (about $5,900) for the families of the deceased.

The Navy said the speedboat was undergoing engine trials as the full investigation of the accident is underway.