Turning down the army's request for an internal inquiry into the alleged illegal immigration racket involving some of its top brass, the defence ministry has asked the Central Bureau of Investigation to conduct a thorough probe into the scam.

The CBI, in response to a letter from Defence Secretary Vijay Singh [Images], has asked him to file a complaint before it so that an FIR could be lodged in the case, official sources said. It has also sought all records pertaining to the case.

The racket came to light earlier this month when four persons were detained at the Indira Gandhi [Images] International Airport in Delhi while trying to leave the country on official army passports, prompting the authorities to investigate for possible links with a larger illegal immigration network.

The four detained persons were carrying official white passports issued to the Army headquarters band for a performance in Germany [Images].

According to sources, an Army soldier Suresh Babu had allegedly prepared these travel documents and sold them for nearly Rs 50,000 each.

During investigations, Babu had claimed that he had prepared the passports in the past as well, the sources said.

The sources said that Babu had alleged that he had prepared diplomatic passports illegally for a senior official and his wife during their visit to Malaysia. He has also named a colonel working in the Ceremonial and Welfare Directorate at the army headquarters.

While the army informed the ministry that it was carrying out investigations into the case and would submit a final report soon as it was a "single" case involving a soldier, the ministry refused to buy the theory and ordered a thorough CBI probe into the case as it suspected involvement of some senior officials of the army and the Ministry of External Affairs.

The CBI has also made it clear that while investigating the matter, no parallel probe shall take place as it would affect their investigation and the army could withhold some documents on the pretext of its own probe.

In this case also, Germany was the target country for human trafficking.

In 2005, the CBI had registered a case against Special Secretary of External Affairs Ministry Rakesh Kumar for his
alleged involvement in human trafficking during his tenure in the Indian Council for Cultural Relations as nine members of an official dance troupe went missing.

According to initial findings of the Army probe, 37 personnel, including officers, were authorised to go to Germany.

An additional 10 forms for standby personnel were also filled. These standby passports were supposed to be returned to the external affairs ministry.

However, the sources claimed that photographs of non-army personnel were affixed to four of these standby passports, which were verified and signed by a senior army officer.

After the band left for Germany, the extra passports were not returned to the MEA.

The ministry has told the army probe team that it was unable to locate the files pertaining to the visit of the band.

This is the second such case this year involving the use of the official diplomatic white passport.

Earlier, a Bharatiya Janata Party Parliamentarian Babubhai Katara was caught trying to smuggle out a woman on a diplomatic passport.