NEW DELHI, Dec 21 (Reuters) - India's federal police filedcharges against Bharti Airtel Ltd and Vodafone GroupPlc's India unit on Friday as part of a probe intoalleged corruption in allocation of mobile phone airwaves adecade ago, a lawyer said. The charges include criminal conspiracy, A.K. Singh, alawyer for the Central Bureau of Investigation (CBI), toldreporters. He said no executives of the companies were charged. The CBI had last year registered cases against thecompanies, two former telecoms ministry officials and others,over alleged irregularities in airwave grants during theprevious government led by the Bharatiya Janata Party (BJP),which is now in opposition.