Anwar Ibrahim today urged former deputy prime minister Muhyiddin Yassin to get his new party up and running immediately.

"Now he has to gerakkan (run) the party," Anwar said outside the Syariah High Court in Shah Alam.

The PKR de facto chief said this as he was escorted out of the court, after testifying in his qazaf complaint against senior lawyer Muhammad Shafee Abdullah.

Anwar, who is the former opposition leader, was asked to comment on Parti Pribumi Bersatu Malaysia (Bersatu), the new party for which Muhyiddin filed the registration papers on Tuesday.

Muhyiddin is to be the new party's president, while former prime minister Dr Mahathir Mohamad will be the chairperson.

Last month it was reported that Anwar was awaiting Muhyiddin's next move when word got out that Mahathir and Muhyiddin would form a new party.

In response, the PKR defacto leader said that he welcomed the new party and called it a positive development. This is despite he had earlier penned a scathing letter warning the party members to be wary of Mahathir.

However, Bersatu has seen some prominent people shying away from the party, such as former Batu Kawan Umno vice-chief Khairuddin Abu Hassan, and former minister in the Prime Minister's Department, Zaid Ibrahim.

Earlier, Anwar's supporters brought a birthday cake for the PKR de-facto leader who celebrated his 69th birthday yesterday.

However, the Prison Department guards did not allow it to be presented to him, resulting in the supporters sharing the cake among themselves.