Earlier on Thursday, the government of the state of Jammu and Kashmir placed the separatist leaders under house arrest in the city of Srinagar before releasing them a few hours later.
Talks between India's National Security Adviser Ajit Doval and Aziz are due to be held on August 23 and 24 in New Delhi.
Pakistani High Commissioner in India Abdul Basit has invited the Kashmiri separatist leaders to meet with Aziz in Delhi ahead of the talks. India has condemned the suggestion.
The Jammu and Kashmir region has been disputed by India and Pakistan since the end of British rule in 1947. Following a number of military conflicts, the countries agreed to a ceasefire in 2003. However, both sides have repeatedly accused each other of violating the truce.