Imran Khan used an address marking Pakistan's Independence Day on Wednesday to criticise India for its actions in disputed Kashmir.
"Independence Day is an opportunity for great happiness, but today we are saddened by the plight of our Kashmiri brothers in occupied Jammu and Kashmir who are victims of Indian oppression," the Pakistan Prime Minister said.
"I assure my Kashmiri brothers that we stand with them."
India revoked the special status of its administered part of Kashmir, known as Jammu and Kashmir, on August 5 and moved to quell widespread unrest by shutting down communications and clamping down on freedom of movement.
Islamabad retaliated by suspending bilateral trade and all public transport links with India, as well as expelling New Delhi's ambassador to Islamabad.
India administers the populous Kashmir Valley and the region around Jammu city, while Pakistan controls a wedge of territory in the west known as Azad Kashmir.
India's revocation of special status for Jammu and Kashmir blocks the state's right to frame its own laws and allows non-residents to buy property there.
Indian Prime Minister Narendra Modi's government has said old laws prohibiting people from outside Kashmir from buying property, settling there and taking up government jobs had hindered its development.
Restrictions were lifted in five districts of Jammu and in nine Kashmir districts on Monday, India's Home Ministry said.
It said there would be heightened security for both Pakistan and India's Independence Day celebrations and for Muslim Friday prayers.
Mr Khan travelled to Muzaffarabad, capital of Azad Kashmir, where he is expected to address the state parliament.
In Islamabad, posters urged residents to express solidarity with Kashmiris and roadside vendors sold Azad Kashmir flags as well as the Pakistan flag commonly displayed on August 14.
Pakistan's government has also said India's Independence Day, which falls on Thursday, will be observed as a "Black Day", with flags on government buildings flown at half mast to protest against India's decision.
