One in three hand grenades used by Indian soldiers is a dud, while their rifles are no match for those of extremists, a newspaper report said Monday.

The Times of India said 30 percent of grenades fail to blow up after being thrown by troops in combat situations, while those that do work take four seconds to explode -- 1.5 seconds longer than those used by militants.

Indian soldiers normally carry four grenades in counter-insurgency operations, Colonel R.S.N. Singh, from the Indian Defence Review, was quoted as saying.

"Even a single dud can prove disastrous as it would leave the soldier vulnerable," he added.

The criticism comes after deadly attacks in Mumbai last year left 166 people dead, an incident that highlighted the out-of-date and ineffective weaponry used by police in the country's financial capital.

Officers initially tried to take on heavily-armed Islamist militants using bamboo sticks, revolvers and British colonial-era bolt-action rifles until commandos arrived.

Retired army colonel U.S. Rathore said Indian soldiers still used hand grenades dating back to World War II and suggested their malfunction could be due to chemical degradation.

The newspaper, which based its report on unnamed military and defence sources, said soldiers had also complained about the Indian Army's standard issue Insas assault rifle.

"The barrel overheats with continuous firing," one source told The Times. "Oil spillage while firing is also a major trouble."

The rifle's lack of a rapid-fire feature also fails to match up to the extremists' weapon of choice, the Russian-made AK-47, the report said.