Among those speaking at the Kashmir rallies on Friday was Hafiz Muhammad Saeed, the head of Jamaat-ud-Dawa - which has been accused of being a political front for Lashkar-e-Taiba, the group blamed by India for the attacks.
Saeed told an audience in the eastern city of Lahore that Kashmir was one of the most important global issues and expressed his support for predominantly Muslim Kashmir to be given the right to self-determination.
"We are not against dialogue with India, but composite dialogue should include Indian intervention in East Pakistan [Bangladesh] as well as the issues of Joonagarh, Monawader as well as Babri Masjid," he said, referring to a mosque in India demolished in 1992.
Saeed denies any involvement in the Mumbai attacks and in June was released from house arrest by a Lahore court which found insufficient evidence for his continued detention.
In recent years, February 5, has come to be known as a day of solidarity with the Kashmiri people. The date has no specific significance, but is a public holiday in Pakistan.
Pakistan observed a one-minute silence at 10am (0500 GMT) as a mark of respect to the more than 47,000 people killed since separatists started fighting in 1989.
Raja Nassim, a provincial government official of Pakistan-administered Kashmir, said that the day was marked to "give assurance to the people of occupied Kashmir" that they are supported throughout Pakistan.
Anti-India sentiments run deep in Muslim-majority areas of Indian Kashmir, where more than a dozen groups have been fighting for its independence or its merger with neighbouring Pakistan.
Ravi Sawney, the former director-general of Indian Military Intelligence, said he was "saddened" by Islamabad's apparent support for the separatist fighters in Kashmir.
"Pakistan should discourage these career terrorists," he told Al Jazeera from New Delhi.
"You get a feeling they have a certain amount of encouragement, otherwise their activities would be curbed and their annoucements would be muted.
"However they seem to be addressing the rallies openly and not being arrested which means their is a certain amount of government encouragement."
In Srinigar, in Indian Kashmir, troops sealed off areas and arrested dozens of activists planning to protest over the death of a 14-year-old Muslim boy on Sunday.
His death has sparked days of angry protests against Indian rule and left about 150 protesters and policemen injured.