The CBI has approached the Interpol to locate billionaire jewellery designer Nirav Modi and his family who had left the country in the first week of January, weeks before scam was reported to the agency, officials said.

Officials said the CBI approached the Interpol with a request for issuing Diffusion Notice which was aimed at locating an individual.

"This (diffusion) is less formal than a notice but is also used to request the arrest or location of an individual or additional information in relation to a police investigation. A diffusion is circulated directly by an NCB (CBI in this case) to the member countries of their choice, or to the entire INTERPOL membership and is simultaneously recorded in Interpol’s Information System," the website of Interpol says.

The CBI was confident about getting a location of Modi and his family by today, they said.

Modi, who was alleged to have carried out fraudulent transactions worth over Rs 11,400 crore in Punjab National Bank, had left the country in the first week.of January.

The 46-year old, who holds an Indian passport, left India on January 1, while his brother Nishal, a Belgian citizen, departed from the country on same day.

However, whether they travelled together has to be probed, they said.

Modi's wife Ami, a US citizen, left on January 6 and his uncle and business partner Mehul Choksi, the promoter of Gitanjali jewellery chain, left on January 4, the officials said.

The CBI and the Enforcement Directorate have approached the government seeking revocation of passports of Modi and Choksi.

The billionaire diamond merchant, a regular on the lists of rich and famous Indians since 2013, was booked by the CBI, along with wife, brother and Choksi on January 31, for allegedly cheating the state-run Punjab National Bank to the tune of Rs 280 crore.

The bank again approached the CBI within a fortnight of the first complaint giving details of more transactions which were over Rs 11,400 crore.

The question as to why the PNB did not send a complaint to the CBI and decided to give it in tranches is also under the scanner of the agency, they said.

The bank has claimed in three complaints to the CBI that so far it has detected 150 Letters of Undertaking (LoUs) which were fraudulently issued by its officials in connivance with Modi and the other accused in the case, the officials said.

An LoU is a letter of comfort issued by one bank to branches of other banks, based on which foreign branches offer credit to buyers.