A meeting of Indian officials and telecoms operators on whether to restrict Research in Motion's (RIM) BlackBerry services over national security fears was inconclusive, a top government official said on Thursday.

Worried about security, India's interior ministry held the meeting with at least one operator on Thursday to look at how security services could access encryption details for the smartphone, the latest global headache for maker RIM.

State-run BSNL attended the meeting, but it was not clear whether any of the major private carriers attended.

A telecoms ministry official, who asked not to be named, said the talks remained "inconclusive" after the meeting.

A senior government official said on Wednesday that the government could ask mobile phone operators to block BlackBerry messaging and e-mail until RIM provides access to data transmitted over the handset.

Bharti Airtel and Vodafone's India unit are the largest providers of BlackBerry services in India, the world's fastest growing market.

A shutdown would affect one million of the smartphone's 41 million users.

India is one of RIM's fastest growing markets.

If a shutdown takes effect, BlackBerry users in India would only be able to use the devices for phone calls and internet browsing.

In a matter of a few weeks the BlackBerry device - long the darling of the world's CEOs and politicians, including US President Barack Obama - has become the target for its encrypted email and messaging services.