India's parliament was thrown into disarray Tuesday as opposition lawmakers protested at mass conversions to Hinduism, with the uproar threatening to disrupt Prime Minister Narendra Modi's legislative agenda.

Angry lawmakers stormed the well of parliament's upper house forcing its shutdown for the day. They demanded Modi make a statement on reports of poor Muslims being coerced into converting to India's majority religion.

"The house will not run until the prime minister comes for discussion over the communal incidents and forced conversions issue," Derek O'Brien, from the regional opposition All India Trinamool Congress, told reporters.

The warning threatens to disrupt the Modi government's plans to pass a series of major economic reforms through parliament, with just four days of the current session remaining.

The right-wing government, which swept to power at national elections in May on a pledge to reform and revive the economy, wants to pass a bill to open the insurance sector to foreign investment.

The government was also inching closer to finalising agreement with India's states on taxation reform by introducing a national sales tax, according to local media reports on Tuesday.

Finance Minister Arun Jaitley was hopeful of tabling a constitutional amendment in the current parliament for introduction of the long-awaited goods and services tax (GST), to replace a myriad of overlapping state duties that deter investment.

A hardline group linked to Modi's Hindu nationalist Bharatiya Janata Party (BJP) has been accused of converting some 50 slum-dwelling Muslim families last week in the Taj Mahal city of Agra.

One of the converts told AFP they were promised ration cards and other financial incentives if they went ahead with the conversions.

A BJP lawmaker has since announced plans for an even biggger conversion event of Christians and Muslims on Christmas Day in the northern town of Aligarh.

Critics say Hindu hardline groups have become more emboldened since the BJP was elected, with rising communal tensions in the Hindu-majority but multi-faith country.

Parliament under the previous Congress-led government was routinely paralysed, with shouting, jeering and protests frequently forcing adjournments.

Modi's BJP won the biggest mandate in 30 years in May, raising hopes it would have the numbers to control parliament and ensure the smooth passage of legislation.

But the BJP lacks a majority in the upper house, where Congress and regional lawmakers have combined to protest at a range of issues.