In view of this, PAS fully supports the merger "without any reservations", he said when contacted.
"Certainly two parties which can have a common stand and choose to be united is better than two different parties," he added.
The PAS leader said the merger which will see the birth of Parti Keadilan Rakyat will also increase communication in the opposition front.
On the differences that may arise among the members of Keadilan and PRM, Hassan said it was normal to have differences but members must focus on the big picture, which is to fight Barisan Nasional.
"If the members can keep this in mind, a lot of problems can be solved easily," he added.
BA was formed in 1999 and at that time it also included DAP. However, the party exited the front last year after crossing swords with PAS over its theocratic ambitions.
Meanwhile, when asked to comment on the merger, Umno vice-president Muhammad Muhammad Taib simply replied: "I just want to wish them luck."
Keadilan and PRM signed a memorandum of understanding (MoU) today in order to expedite the much delayed merger.
Keadilan president Dr Wan Azizah Wan Ismail and PRM president Dr Syed Husin Ali inked the MoU at the Keadilan headquarters in Petaling Jaya, Selangor, this afternoon.