The Pakistan Bureau of Statistics on Friday failed to allay the reservations put forward by senators with respect to the 2017 census, with Chief Census Commissioner Asif Bajwa rejecting outright all concerns raised regarding alleged irregularities in census data.

The Senate has subsequently decided to summon the chairman of the National Database and Registration Authority (Nadra) for more information.

Bajwa had on Friday appeared before a special committee of the Senate— comprising the whole house— to look into perceived issues surrounding the 2017 census.

Bajwa, in his briefing, outright rejected the allegation that the census results had been manipulated and that the population of Karachi had been deliberately understated.

He said that the entire population of Karachi and Lahore was counted as per the record of computerised national identity cards and voter lists available with the authorities.

He maintained that the census had been carried out in a transparent manner and that the data obtained had already been verified with statistics recorded by the army during the counting process.

"There was no difference between the record of the government and the army," he added.

Senator Taj Haider, however, questioned the census results, saying that he had obtained data on the population of Karachi in 2013 from Nadra. According to the document, the population of the city was then more than 25.6 million individuals, he said, adding that he believed that the record had been tempered during the ongoing census.

In response to the objection, Bajwa claimed that he has talked to Narda but the authority was not willing to take ownership of the list being spoken about by the senator.

The Senate subsequently decided to summon the Nadra chairman for clarification and recommended the re-verification of data from three blocks.

The committee also asked Bajwa to speed up the process of compiling the census data.

On the occasion, some senators from Fata handed written complaints to the commissioner in connection with census data and directed him to verify if the complaints were justified.

When asked about migration to the country since 1947, Bajwa rescued himself by saying that he was unable to verify any figures. He further said that he would be able to disclose the actual numbers of foreigners who are residing in the country after completion of the census work.