The two Sufi clerics from Delhi who went missing on 15 March, on their tour of Pakistan, are reported to be in the custody of the Pakistan's intelligence agencies.
The duo, Syed Asif Nizami and his nephew Nazim Ali Nizami are part of the family that runs the Nizamuddin Dargah in New Delhi, and were visiting Pakistan to see Syed Nizami's sister who lives in Lahore.
Sources say they were detained by the Pakistani intelligence agencies when they landed in the country to meet their relatives.
Indian officials suspect that either militant groups or Pakistan's intelligence agencies may have abducted two Sufi clerics from New Delhi who were visiting the neighbouring country but went missing yesterday.
The foreign office had yesterday formally communicated its concerns over the disappearance of 82-year-old Syed Asif Nizami and his 66-year-old nephew Nazim Ali Nizami to Pakistan.
The duo was last spotted at the Data Darbar Sufi shrine in Lahore and has been missing since Wednesday evening. Pakistan had claimed that Asif was allowed to go to Karachi, but Nazim was stopped at the airport itself. However Indian agencies have learnt that the duo was picked up and detained by the agencies in Pakistan. "We are expecting a communication from them shortly on the issue, Indian agencies had said.
On Friday, foreign minister Sushma Swaraj publicly sought an "update" from Pakistan.
"We have taken up this matter with government of Pakistan and requested them for an update on both the Indian nationals in Pakistan," Sushma wrote on micro-blogging site Twitter on Friday morning.
Pakistan foreign ministry spokesperson Nafees Zakaria confirmed the Indian request in a media briefing and said Pakistan's interior ministry was investigating the incident.
The two clerics flew into Lahore on 8 March, and were to return on 20 March. The clerics visited the shrines of Khawaja Fariduddin Ganjshakar - widely known as Baba Farid - just outside Lahore and the Data Darbar inside Lahore, according to photos they shared with their families, officials said.
They were boarding a flight from Lahore to Karachi when they were stopped - the older man was asked to continue on the plane, while the younger man was asked to stay back, according to a call Nazim made to his family, officials said.
The phones of both the clerics have since been switched off.
Pakistan's extremist militant groups view Sufism as a violation of the tenets of Islam, and have targeted Sufi shrines and gatherings. In February, terrorists bombed a Sufi shrine in Sindh province, killing over 70 people (See: Over 100 'terrorists' killed in Pak raids after attack on Sufi shrine).
While Pakistani officials did not confirm or deny the disappearance of the two clerics, at least one Pakistan official suggested that the two might have been detained because of improper documents.