Spokesman Basil al-Khateeb said that despite the release of some 70 hostages since Tuesday's mass kidnapping, between 70 and 80 remained in captivity.
"Thirty-two were released today (Wednesday), while the others were freed yesterday," Khateeb said.
The spokesman acknowledged that it was not known exactly how many ministry staff and visitors had been in the scientific research institute at the time of the raid but said the minister would not return to work until all had been released.
"The minister has stopped working," said Khateeb.
Ujaili had said in the immediate aftermath of the kidnapping that around 100 people were believed to have been taken hostage.
Earlier government spokesman Ali al-Dabbagh played down the scale of the kidnapping insisting that only 39 people had been abducted, of whom all but two had been freed.
Ujaili is one of the ministers in the Shia-led national unity government representing Iraq's Sunni Arab minority.

Copyright AFP (Agence France-Presse), 2006