Pakistani Prime Minister Imran Khan on Wednesday branded India an "oppressor and aggressor" a year after New Delhi imposed direct rule in Kashmir.
Protests were planned across Pakistan to mark the anniversary of New Delhi stripping Muslim-majority Kashmir of its semi-autonomous status, a move that outraged Islamabad.
"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".
Prime Minister Narendra Modi's government had promised the move would bring peace and prosperity to 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.
Police were enforcing tight restrictions in Kashmir on Wednesday, where religious and political groups had called on residents to observe a "black day".
In the Pakistani capital Islamabad, a one-minute silence was held, along with a rally led by President Arif Alvi.
"India has learned from Israel how to change the demography (of Kashmir)," Alvi told the rally
Hundreds of billboards and banners displayed graphic images purportedly of human rights violations by Indian authorities in Kashmir.
Khan led a rally through Muzaffarabad, the capital of Pakistan-administered-Kashmir, where a few thousand people had gathered. He was due to address the region's legislative assembly.
Dozens of rallies are expected in other major Pakistani cities too.
On Tuesday, Pakistan released a new official map showing all of Kashmir as its territory.
Tensions spiralled between the nuclear-armed neighbours after India revoked Kashmir's autonomy and imposed movement and communications restrictions to quell unrest.
Pakistan has repeatedly likened Indian Prime Minister Narendra Modi to Adolf Hitler and called for international intervention.