New Delhi, In a major boost to the Central Bureau of Investigation's (CBI) probe into the Rs 13,500 crore Punjab National Bank (PNB) fraud case, UK Home Secretary Priti Patel has approved the extradition of fugitive diamantaire Nirav Modi, sources said on Friday.

"The UK Home Secretary has approved the extradition request of Nirav Modi," a CBI source related to the probe told IANS.

Asked how long will it take for the CBI will bring back the businessman, who has been lodged in a prison in London since his arrest in March 2019, the source said that if Nirav Modi files an appeal, then it may take some time.

On February 25 this year, a UK court allowed extradition of Nirav Modi in the Rs 13,500 crore PNB scam case.

The District Judge at the Westminster Magistrates' Court, Samuel Goozee, accepted the prima facie evidence against Nirav Modi for money laundering, saying: "Many of these are a matter for trial in India. I am satisfied again that there is evidence that he could be convicted," according to reports.

The CBI had then dubbed the UK court judgement as a "significant" achievement in its efforts to curb corruption.

The CBI in a statement had said that the UK court ruling is "a reminder that fugitives, who have eluded the process of law after commission of large value frauds, cannot consider themselves above the process merely because they have changed jurisdictions".

Nirav Modi was arrested on an extradition warrant on March 19, 2019 on charges of money laundering, conspiring to destroy evidence and intimidating witnesses.

He is facing probe by the CBI for a large-scale fraud upon PNB through fraudulently obtaining LoUs or loan agreements. He is also being probed by the Enforcement Directorate (ED) in a case relating to the laundering of the proceeds of that fraud.

Meanwhile, he also faces two additional charges of "causing disappearance of evidence" and "intimidating witnesses" or "criminal intimidation to cause death", which were added on to the CBI case.

The ED has attached several assets of Nirav Modi running into crores of rupees in connection with the case.

Nirav Modi's uncle, Mehul Choksi of Geetanjali group, who is believed believed to be in Antigua, is also being probed in connection with the case.