India's opposition has demanded the resignation of Congress Prime Minister Manmohan Singh, raising the stakes after forcing the exit of two cabinet ministers over corruption scandals.
Pressure has been building for months on the premier, who is widely accused of ineffectiveness while overseeing a sharp economic slowdown and turning a blind eye to a slew of graft controversies that have alarmed foreign investors.
"The government is facing serious corruption allegations," Rajnath Singh, president of the Hindu nationalist opposition Bharatiya Janata Party (BJP) said on Saturday.
"If the prime minister honestly introspects about what should be done to strengthen the faith of the people in the government, he will find he has no other option but to resign," Rajnath Singh told reporters in New Delhi.
His calls came after law minister Ashwani Kumar quit on what the media dubbed "Black Friday" over government interference in a police probe, while railway minister Pawan Bansal resigned over a separate bribe allegation controversy.
The resignations have heightened speculation about how long the minority left-leaning government, clinging to power with the support of two regional parties, can stagger on. Its five-year mandate expires in May 2014.
"They definitely are very vulnerable now," political analyst Subhash Agrawal of think-tank India Focus told AFP.
Congress fought on Saturday to contain the fallout, insisting the ministers' resignations showed it had zero tolerance for graft.
Congress "has once again clearly shown if there is suspicion on anyone - even if unproved - they are made to resign", party leader Digvijaya Singh said.
Kumar insisted on Saturday he was innocent of wrongdoing and had quit as a "loyal (party) footsoldier" to end "unnecessary controversy".
"My conscience remains clear and I believe I will stand vindicated," he said.
The government told telecom minister Kapil Sibal, a prominent lawyer, to double up as law minister while railways went to Transport Minister CP Joshi.
Bansal, a veteran Congress member, stepped down as railways minister a week after police arrested his nephew Vijay Singla for allegedly extracting 900 million rupees ($160,000) from a railway official to arrange his promotion.
Bansal denied any knowledge of his nephew's alleged activities but the opposition charged it was impossible for him not to have been aware of them.
The law minister's exit came after he and officials from Singh's office and the coal ministry substantially changed a police inquiry report into the alleged allocation of mines at giveaway prices.
Singh, 80, in addition to being premier, was coal minister for part of the period under police scrutiny, fuelling opposition demands for him to also quit.
News magazine India Today has asserted Singh, pioneer of India's dramatic economic reforms in the 1990s and who had been reknowned for his probity, is "fast becoming a prime embarrassment for the government" for failing to stem the tide of scandals on his watch.
"The Teflon coating has worn off (the prime minister), not wholly but very substantially," said TN Ninan, publisher of the Business Standard newspaper.