The latest move to de-register the party was made known to PKR officials in a letter from the Registrar of Societies (ROS).
Anwar described the latest threat a "desperate" move.
"This is the work of desperate UMNO leaders who want to keep punishing the people," he replied during the online "Question time" session hosted by Yahoo! Malaysia.
It revolves around the party's sacking of one "Rajagopal Andaikkalam" in 2009, for which ROS claimed PKR had not followed proper procedures based on Article 32.2.1 of the party's constitution.
However, Saifuddin pointed out two mistakes in the notice.
Firstly, he said such an article did not exist in PKR's constitution, and secondly, there was no such person with such a name, although there was another member by the name Jayagopal a/l Andaikallam who had been sacked.
"Even if it was a typo, Article 32 has nothing to do with disciplinary issues or the Disciplinary Board," he said.
Meanwhile, PAS vice president Salahuddin Ayub (left) said the move to de-register a political party when general election was around the corner was uncalled for.
"The 13th general election is just around the corner as we all know. The government should not take the opportunity to go to polls by banning PKR," he told reporters at the PAS headquarters.