Separatists held a human rights protest in Srinagar on Monday
Amnesty International has urged the Indian government to launch an urgent investigation into some 1,000 unmarked graves found in the Kashmir valley.
A Kashmir rights group had earlier said it had found the graves across a dozen villages in the area around the town of Uri over a 14-month period.
Amnesty said these may be victims of unlawful killings and "disappearances".
The Indian army and militants have been accused of numerous human rights abuses in Kashmir over the past two decades.
More than a dozen Islamic groups have been fighting Indian administration.
Amnesty's statement read: "The grave sites are believed to contain the remains of victims of unlawful killings, enforced disappearances, torture and other abuses which occurred in the context of armed conflict persisting in the state since 1989."
It called for "prompt, thorough, independent and impartial investigations".
Amnesty said the grave sites "must be secured in order to preserve the evidence".
Last week police in Indian-administered Kashmir rejected a demand for action to identify the bodies.
The inspector general of police in the Kashmir valley, SM Sahai, said police had investigated all cases of disappearances reported to them and had registered cases for investigation wherever necessary.
On Monday, senior leaders of the main separatist group, the All Parties Hurriyat Conference, led a protest in Srinagar against what they called gross human rights abuses by security forces.
The BBC's Altaf Hussain says that one of the locations identified by the Kashmir-based rights group, the Association of the Parents of Disappeared Persons (APDP), is Kichama village, 62km (39 miles) from Srinagar.
He says that none of the more than 200 apparent graves there has anything to identify the names of the deceased.
The villagers say they have no idea who they were and that the police told them the men were foreign militants killed in fighting with the Indian troops.
The APDP says more than 8,000 people have disappeared in Kashmir over the past two decades.
The government has given conflicting figures, ranging from 3,700 to 111.