India's main opposition Congress party filed a complaint to the Election Commission Monday accusing Hindu nationalist Prime Minister Narendra Modi of "blatantly targeting" minority Muslims in a campaign speech.

The world's most populous country is constitutionally secular and its election code bans canvassing based on "communal feelings".

Modi's muscular Hindu-first politics is a key part of his electoral appeal and his opponents accuse him of marginalising India's 200 million Muslim population.

The prime minister usually steers away from explicit references to religion -- the word "Hindu" does not appear in his Bharatiya Janata Party's (BJP) 76-page election manifesto.

But at a weekend election rally in Rajasthan, Modi claimed a previous Congress government had said that "Muslims have the first right over the nation's wealth".

He said if Congress won "it will be distributed among those who have more children. It will be distributed to the infiltrators."

"Do you think your hard-earned money should be given to infiltrators? Would you accept this?"

Critics said the phrases were references to Muslims.

In its complaint to the Election Commission, the Congress party said the "divisive, objectionable and malicious" comments were targeted at "a particular religious community" and amounted to "blatant and direct violations of electoral laws".

They were "far worse than any ever made by a sitting Prime Minister in the history of India", the complaint said.

Congress party spokesperson Abhishek Manu Singhvi told reporters outside the Commission's office: "We hope concrete action will be taken."

Modi and the BJP are widely expected to coast to victory in India's marathon elections, which began last Friday and with the results due on June 4.

Earlier this year, Modi presided over the inauguration of a grand temple to the deity Ram, built on the site of a centuries-old mosque razed by Hindu zealots.

The BJP has frequently invoked the temple on the campaign trail.

BJP spokesperson Gaurav Bhatia told reporters Monday that Modi was calling "a spade a spade" and his remarks resonated with what people thought.