NEW DELHI (AFP) - India's election authorities Friday ordered police to investigate remarks by a top aide of prime ministerial frontrunner Narendra Modi that were allegedly aimed at inciting communal violence.

The powerful Election Commission also barred Modi's aide Amit Shah, 50, from holding public rallies, meetings and roadshows to keep a check on what it called his "undesirable activities".

Shah has been leading the opposition Bharatiya Janata Party's (BJP) general election campaign in the northern Uttar Pradesh state where Hindus dominate but there is a sizeable Muslim community.

The close confidante to Modi has been in the eye of a public storm after he reportedly told several Hindu leaders last week to seek "revenge" at the ballot box.

He was speaking in a part of the state torn apart by deadly Hindu-Muslim violence last September that left some 50 people dead.

The commission also ordered a similar probe into statements by Azam Khan, a leader of the regional Samajwadi Party which is the ruling party in Uttar Pradesh.

Khan reportedly used derogatory language against Modi, the hardline Hindu nationalist who is widely tipped to become India's next prime minister after the marathon elections wind up in May.

The commission said the alleged "provocative" and "highly inflammatory" statements of the two political leaders were "being made with deliberate and malicious intention" of disturbing peace and harmony in the country.

It also criticised the state authorities for not acting against the leaders with the "required alacrity".

The national election campaign, which has largely focused on development, has taken a religious tone in recent days.

Modi, 63, has accused ruling Congress president Sonia Gandhi of failing to deliver on pledges to improve the lives of Muslims, who at 13 per cent of the population are the largest religious minority in Hindu-majority but officially secular India.

Modi, chief minister of the prosperous western state of Gujarat, is reviled by many of India's Muslims due to religious riots that swept the state in 2002 when he began his rule.

At least 1,000 people, mostly Muslims, were killed but Modi has denied critics' claims he was slow to curb the bloodshed.

Opinion polls suggest Modi is set to lead the BJP to power after a decade in the political wilderness. He has been campaigning on a promise of reviving the country's battered economy and creating jobs.

The multi-phase elections, which started April 7, will close May 12 with results due four days later.