Pakistan's Interior Minister Rehman Malik Tuesday phoned his Indian counterpart P. Chidambaram to thank him for the release of singer Rahat Fateh Ali Khan, detained at the airport here for carrying undisclosed foreign currency of over $100, 000.

"The two ministers spoke to each other. Rehman Malik thanked Chidambaram for ensuring the early release of Rahat Ali Khan, " a spokesperson in the Pakistan High Commission here told.

The spokesperson said Malik assured Chidambaram of Rahat's cooperation in probe into the case, being investigated by the Directorate of Revenue Intelligence (DRI).

Rahat and his two colleagues, Maroof and event manager Chitresh Shirivastava, were detained at the Delhi's Indira Gandhi International Airport when they were about to take off for Pakistan Sunday night.

They have been charged with carrying undisclosed foreign currency of over $100, 000.

They were freed Monday evening but have been asked to appear before the DRI Feb 17.