Pakistani Prime Minister Imran Khan branded India an "oppressor and aggressor" on Wednesday, a year after New Delhi imposed direct rule on Indian-administered Kashmir.

Solidarity marches were held in all major Pakistani cities to mark the anniversary of New Delhi stripping Muslim-majority Indian Kashmir of its semi-autonomous status, a move that outraged Islamabad.

Kashmir, a disputed Himalayan territory, has been split since 1947 between India and Pakistan, both of which claim it in full and have fought wars over it.

"India stands exposed before the world, yet again, as an oppressor and aggressor," Khan said in a statement.

"Its so-called secular and democratic credentials stand fully discredited," he added, calling India's action last year a "crime against humanity".

Khan led a march through Muzaffarabad, the capital of Pakistan-administered-Kashmir, before addressing the region's legislative assembly.

Across the city, more than 2,000 people turned out at a series of anti-India protests.

"We ask the world to give Kashmiris their right of self-determination, otherwise we will cross the Line of Control and help our brothers on the other side with arms,", Arslan Ahmad, a refugee who fled Indian-administered Kashmir, told AFP.

"Half of my family is under siege in Indian-occupied Kashmir, my mother is dying to meet her sister, this dispute has left our generations torn apart," 31-year old Usman Mir added.

Police were enforcing tight restrictions in Indian-administered Kashmir on Wednesday, where religious and political groups had called on residents to observe a "black day".

Pakistani President Arif Alvi led a rally in solidarity with the people of Indian-administered Kashmir in Islamabad
Pakistani President Arif Alvi led a rally in solidarity with the people of Indian-administered Kashmir in Islamabad AFP / Aamir QURESHI

Prime Minister Narendra Modi's Hindu nationalist government had promised the move would bring peace and prosperity to Indian Kashmir after three decades of violence sparked by an anti-India uprising.

Pakistan, however, has alleged it is a violation of the rights of Kashmiri people.

Khan accused India of trying to turn Kashmir's Muslim majority into a minority by ending restrictions on outsiders buying up property "in blatant violation of... UN Security Council Resolutions and international laws".

The change in rules has sparked fears that the Modi government is pursuing an Israel-style "settler" project.

A referendum in Kashmir mandated by a UN resolution in 1948 has never taken place.

"India has learned from Israel how to change the demography (of Kashmir)," President Arif Alvi told a rally in the Pakistani capital Islamabad, which observed a one-minute silence.

Hundreds of billboards and banners displayed graphic images purportedly of human rights violations by Indian authorities in Kashmir.

On Tuesday, Pakistan released a new official map showing all of Kashmir as its territory.

The Pakistan military, meanwhile, said Indian troops had fired a shell across the de-facto border, killing a young woman and wounding six other people.

Such exchanges are common along the Kashmir demarcation line, with shells blasted in both directions.

Pakistan has repeatedly likened Modi to Adolf Hitler and called for international intervention.