Which party called for a reunion of India and Pakistan in Akhand Bharat?

Bharatiya Jana Sangh

Bharatiya Jana Sangha:
The Bharatiya Jana Sangh was founded in 1951 by Shyama Prasad Mukherjee, its lineage traced back to the Rashtriya Swayamsevak Sangh (RSS) and the Hindu Mahasabha.
Jana Sangh emphasized the idea of one country, one culture, and one nation, believing that India could progress and become strong based on its culture and traditions.
The party advocated for the reunification of India and Pakistan in ‘Akhand Bharat’ & opposed granting concessions to religious and cultural minorities.
It actively supported the replacement of English with Hindi as the official language of India and called for India to develop nuclear weapons after China's atomic tests in 1964.