Six Nigerian nationals have been arrested in the Indian city of Mumbai on suspicion of defrauding hundreds of people through text message and spam email scams, police said.

The group was picked up from three properties in a north Mumbai suburb on New Year's Eve, officers said late Monday. All six have been remanded in custody until January 12 pending further investigations.

The arrests come amid concern about an increase in India of spam -- the sending of anonymous unsolicited emails -- and "phishing", when fraudsters obtain personal details from unsuspecting email recipients.

A recent report by the Moscow-based global Internet security firm Kaspersky Lab said that more spam was sent from India than anywhere else in the world in the third quarter of last year.

Experts have urged the government in New Delhi to introduce anti-spam laws and increase public awareness, as spammers, forced out of other countries due to crackdowns, can act with impunity in India.

The police raid in Mumbai seized 14 laptops, 15 datacards, seven memory sticks and 23 mobile phones, as well as printers, fake documents and cash. The electronic equipment has been sent for analysis.

Officers said the six are alleged to have duped recipients into handing over personal details and money by informing them they had become millionaires in a lottery.