Pakistan has initiated hectic efforts to secure the release of famous singer Rahat Fateh Ali Khan detained at New Delhi's Indira Gandhi International Airport on charges of carrying undisclosed foreign currency.

Foreign Secretary Salman Bashir called Indian High Commissioner in Islamabad Sharat Sabarwal and discussed the matter around midnight Sunday. He requested the Indian envoy to ensure that "no official should misbehave with Rahat during interrogation".

Rahat was detained at the Delhi airport Sunday on his way back to Pakistan after attending concerts and award functions in India. More than $100, 000 were recovered from the 15-member troupe.

After over six hours of interrogation by customs officials, he was formally arrested and would be presented in a court Monday morning, Dunya News reported.

Bashir also called up Pakistani High Commissioner to India Shahid Malik and directed him to "take immediate steps for securing release of Rahat".

"The matter should be taken up formally with Indian foreign office, " he said, adding that "contact with Indian authorities for updates in the case must be maintained throughout".

Earlier, Interior Minister Rehman Malik called Shahid Malik and directed him "to provide necessary legal and other consular help to Rahat".

"Regular updates should be given to authorities in Pakistan regarding efforts to resolve the case, " he stressed.

Rahat's brother-in-law, Asim Raza, told Dunya TV that they "received information from the media and were feeling concerned about it". "We are yet to establish any proper contact with the authorities in India although Rahat talked briefly with his wife and asked her to remain hopeful of a positive outcome".

Rahat, the nephew of legendary singer Nusrat Fateh Ali Khan, is popular both in India and Pakistan. Several of his hit songs from Indian films are a rage on both sides of the border, for which he has won several awards, including the recent Filmfare award for "Dil to Bacha Hai Jee".