NEW DELHI (AFP) - India's unruly parliament was paralysed on Monday as new scandals engulfed the Congress-led government, stalling its economic reform drive and leading to opposition calls for the resignation of two ministers.

The government, rocked by repeated controversies, was put on the defensive by charges that the law minister interfered in a criminal probe into the alleged illegal awarding of coalfields at throwaway prices.

The government was also hit by the arrest of the railway minister's nephew who had allegedly demanded a US$160,000 (S$197,068) bribe to arrange a plum promotion for a railway official.

"The resignation of the ministers is a must. No bill should be passed in chaos, and we will not let any bill pass," said lower house opposition leader Sushma Swaraj.

The minority government was not seen in any immediate danger of falling.

But the opposition's decision to stall proceedings made it unlikely it would succeed in passing key reforms to hike foreign investment caps in insurance and other sectors as part of its quest to lure vital overseas funds before the session ends on Friday.

After denials that the government had ever seen the Central Bureau of Investigation draft report into the so-called "Coalgate" scandal, the agency's head admitted top government officials had altered the document.

CBI Director Ranjit Sinha told the Supreme Court on Monday that the draft report "was perused" by Law Minister Ashwani Kumar and "he also made certain changes" while another alteration was made at the behest of the premier's office and the coal ministry.

The main opposition Bharatiya Janata Party (BJP) also went after Railway Minister Pawan Kumar Bansal over the job allegedly offered by his nephew, saying he should resign on "moral" grounds.

"The Congress has converted the government into a money-making machine. Everything is put on sale by ministers. We will not co-operate with this government," said senior BJP leader Ravi Shankar Prasad.

The government rejected calls for the ministers' resignations and urged members to "outshout" the opposition.