Leaders of eight Opposition parties wrote to Prime Minister Narendra Modi on Sunday alleging misuse of central agencies against them after Deputy Chief Minister of Delhi Manish Sisodia was arrested earlier this week.

The Central Bureau of Investigation arrested the Aam Aadmi Party leader on February 26 in a case related to alleged irregularities in Delhi’s now-scrapped liquor policy.

The letter to the prime minister was signed by nine Opposition leaders – the Aam Aadmi Party’s Arvind Kejriwal and Bhagwant Mann, the Rashtriya Janata Dal’s Tejashwi Yadav, Shiv Sena (UBT) leader Uddhav Thackeray, Trinamool Congress chief Mamata Banerjee, Nationalist Congress Party chief Sharad Pawar, Jammu and Kashmir National Conference leader Farooq Abdullah and Bharat Rashtra Samithi chief K Chandrashekhar Rao.

The signatories said that the misuse of central agencies against Opposition parties suggests “that we have transitioned from being a democracy to an autocracy”. They alleged that Sisodia was arrested without any evidence and that the charges against the former Delhi deputy chief minister are part of a political conspiracy.

“Out of the total number of key politicians booked, arrested, raided or interrogated by the investigation agencies under your administration since 2014, the maximum belongs to the opposition,” the letter read. “Interestingly, investigation agencies go slow on cases against opposition politicians who join the BJP [Bharatiya Janata Party].”

The Opposition leaders cited the example of Assam Chief Minister Himanta Biswa Sarma, who was under the scanner of the central agencies in 2014 and 2015 over the Saradha chit fund scam when he was with the Congress.

“However, the case didn’t progress after he [Sarma] joined the BJP,” the letter alleged. “Similarly, former TMC [Trinamool Congress] leaders Suvendu Adhikari and Mukul Roy were under the ED [Enforcement Directorate] and CBI [Central Bureau of Investigation] scanner in the Narada sting operation case, but the cases didn’t progress after they joined the BJP ahead of the assembly election in the state [West Bengal].”

The leaders also asked why the agencies have not investigated the Adani Group after the State Bank of India and the Life Insurance Corporation lost Rs 78,000 crore in market capitalisation in January following the publication of a report by United States-based Hindenburg Research. The report had accused the Indian conglomerate of stock manipulation and improper use of offshore tax havens.

“It is clear that these agencies have their priorities misplaced,” the Opposition leaders alleged. “Following the publication of an international forensic financial research report, SBI and LIC have reportedly lost over Rs 78,000 crores in market capitalisation of their shares due to exposure to a certain firm. Why have the central agencies not been pressed into service to investigate the firm’s financial irregularities despite the public money at stake?”

The Opposition leaders also said that the Centre has waged war against the country’s federal structure by appointing governors who are violating constitutional provisions and hampering governance in states where Opposition parties are in power.

“Be it the Governor of Tamil Nadu, Maharashtra, West Bengal, Punjab, Telangana or the Lt Governor of Delhi - the Governors have become the face of the widening rift between the Centre and states run by the non-BUP governments and threaten the spirit of cooperative federalism,” the leader said. “The misuse of central agencies and constitutional offices like that of the Governor - to settle scores outside of the electoral battlefield is strongly condemnable as it does not bode well for our democracy.”

The parties also said that such misuse of central agencies since 2014 has tarnished their image and raised questions about their autonomy and impartiality.