* Charges related to airwave grants in 2002 * Charges include criminal conspiracy * Bharti shares extend fall 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 the 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,but a former telecommunications ministry official was charged. Shares in Bharti Airtel, India's top mobile phone carrier,extended losses after the charges were filed. The stock was down2.9 percent at 0931 GMT. A Bharti spokesman said he had no immediate comment, while aVodafone India spokesman declined to comment. The companies havepreviously denied any wrongdoing. The latest CBI probe concerns alleged irregularities inallotting mobile spectrum in 2002 during the previous governmentled by the Bharatiya Janata Party, which is now in opposition. The investigation follows a scandal over airwave allocationsin 2008 that rocked the ruling Congress Party-led governmentafter a state auditor said the government may have lost up to$32 billion due to below-market price sales of radio spectrum. Police have charged 19 people and three companies in thatcase and their trials are ongoing. The Supreme Court had asked the CBI to investigate anypossible irregularities in the granting of mobile permits from2001 to 2007. The CBI estimated a potential loss of 8.46 billionIndian rupees ($154 million) in government revenue due to thealleged irregularities in 2002, Singh said.