One of the suspects in the gang rape of a 22-year-old photojournalist in India's financial capital Mumbai has claimed he is a juvenile.

The birth certificate of the accused, shown by his grandmother, reportedly contains clear signs of forgery.

Under India's juvenile law, accused minors face trial only in the juvenile justice court and are sentenced to a maximum of three years' imprisonment if convicted. Suspects not tried under this law could face life imprisonment or the death penalty.

One of the accused in last year's New Delhi gang rape incident is being tried in a juvenile court as he was only 17 when the crime was committed.

In the Mumbai case, the grandmother of Chand Babu Sattat Shaikh, alias Mohammed Abdul, claimed the police did not arrest her grandson but it was she who took him to the police. She has also said the accused was not present at the crime scene. He was the first person arrested in the case.

Of the five suspects, only two have been arrested so far; a hunt is on for the others.

"We have arrested a second accused in the gang-rape case and he has confessed to his involvement. The probe is heading in the right direction and we hope to arrest all other absconding accused soon," Mumbai police commissioner Satyapal Singh told reporters.

The victim remains in hospital, where her condition is stable and she is recovering, her doctors said.