"We demand that PKR retract its statement of not supporting the bill on hudud and issue an open apology.
"If PKR agrees to do the above then we will cooperate with PKR in the Permatang Pauh by-election," said Permatang Pauh PAS head Omar Hassan in a statement Sunday.
Omar said the decision was taken at the division's general meeting on Sunday.
PKR party leaders made their stand clear last month in not supporting the bill.
A statement signed by party leaders Datuk Seri Dr Wan Azizah Wan Ismail, Azmin Ali, Nurul Izzah Anwar, Shamsul Iskandar Md Akin, Rafizi Ramli, Zuraida Kamaruddin and Nik Nazmi Nik Ahmad said they would not support the bill's passage in parliament.
The Permatang Pauh parliamentary by-election is being held following the decision of the Pardons Board to reject the petition for a royal pardon sought by its member of parliament Datuk Seri Anwar Ibrahim through his family, resulting in Anwar losing his eligibility as MP.
Anwar is currently undergoing a five-year prison sentence on a charge of sodomising his former personal assistant Mohd Saiful Bukhari Azlan.
The Election Commission has fixed polling day on May 7, nomination on April 25 and early voting on May 3.