Mobile phones without the mandatory 15-digit unique security code are making ways into the grey market by using clones of the international mobile equipment identity (IMEI) numbers of the genuine sets, the commerce ministry has warned.

Alarmed by the widespread use of mobile phones without the IMEI numbers, mostly coming from China, New Delhi had banned import of such sets from December.

In a letter to the home ministry, the commerce ministry warned that unscrupulous elements are "trying to beat the system by copying the card," commerce and industry minister Anand Sharma told PTI here, adding, "very recently it has brought to our attention."

By using the cloning techniques, IMEI of bona fide mobile sets can be used by anti-social elements. IMEI prevents the use of stolen handsets for making calls and a specific user can be tracked down.

Sharma is in the Finnish capital leading a Ficci-business delegation.