On the last day of Parliament's monsoon session, UPA Chairperson and Congress leader Sonia Gandhi on Friday led her party MPs in their protest against the Narendra Modi government on the controversial Rafale deal, and demanded a JPC probe into it.Holding placards, the Congress leaders assembled near the Gandhi statue in Parliament lawns where they shouted slogans denouncing the government and demanded a JPC probe into the fighter jets' deal.Leader of Opposition in Rajya Sabha Ghulam Nabi Azad, former Defence Minister A.K. Antony, Ambika Soni and senior party lawmakers participated in the protest.Among the other parties which also joined the protest included Trinamool Congress, Communist Party of India (CPI) and Aam Aadmi Party (AAP).Earlier, the Congress members in the Lok Sabha raised slogans during the Zero Hour demanding a JPC probe into the Rafale deal and entered the well of the House. Later, they staged a walkout.The Congress MPs also protested in the Rajya Sabha, disrupting the House proceedings briefly."This is the biggest scam of the world. We demand formation of a Joint Parliamentary Committee to investigate the Rafale deal," Azad said in the Rajya Sabha.Minister of State for Parliamentary Affairs Vijay Goel, however, dimissed the allegations, saying the opposition MPs need to have substantial proof if they accuse the Prime Minister of graft.The Congress members had earlier boycotted a breakfast meeting by Vice President and Rajya Sabha Chairman Venkaiah Naidu in protest against the government's move to pass three bills in the House without any discussion.