The U.N. human rights chief has called for an independent, international investigation into reports of rights violations in the disputed region of Kashmir, laying blame for civilian deaths and injuries on the actions of both India and Pakistan.

In its first report on the region, published on Thursday, the office of Zeid Ra'ad al-Hussein, the U.N. High Commissioner for Human Rights, details "chronic impunity for violations committed by security forces."

The report was written without visiting the region as both sides refused to grant unconditional access to the investigators.

The 49-page report adds to criticism about India's tactics in Kashmir, saying its security forces' use of pellet firing shotguns has caused multiple deaths and injuries.

Al-Hussein called the weapon "inaccurate and deadly".

India and Pakistan have a long history of bitter relations over Kashmir, which both claim.

They have fought two of their three wars since they won independence from British colonialists in 1947 over their competing claims to the region.

India accuses Pakistan of arming and training rebel groups who demand that the territory be united either under Pakistani rule or as an independent country.

Pakistan denies the charge and says it only provides moral and diplomatic support to Kashmiris fighting Indian rule.