Dr Mahathir Mohamad's stalwart Khairuddin Abu Hassan blasted Amanah Youth vice-chief Shazni Munir Mohd Ithnin for questioning the former prime minister's sincerity in reaching out to jailed PKR de facto leader Anwar Ibrahim.

Accusing Munir of trying to "act smart", Khairuddin slammed the Amanah Youth leader for failing to understand the significance of their meeting yesterday.

"This immature child does not understand simple language. We should be thankful that Allah has allowed the meeting between Mahathir and Anwar as the first meeting went well and harmoniously.

"This historic meeting is a meaningful start to strengthen the unity among all opposition parties under the banner of Pakatan Harapan," he said in a statement today.

Khairuddin added that Amanah, as a party under Harapan, should be supporting the gesture instead of setting conditions.

Munir had asked Mahathir to first publicly apologise to Anwar to show his sincerity.

Yesterday, Mahathir made a surprise appearance at the High Court in Kuala Lumpur to show support for Anwar's application to challenge the National Security Act 2016, which grants a council headed by the prime minister emergency-like powers.

It was the first meeting between the two men in 18 years after then prime minister Mahathir sacked his deputy Anwar and had him jailed for sodomy and abuse of power, charges which the latter had claimed were politically motivated.

Anwar was freed in 2004 after the sodomy charge was overturned but he was put behind bars again in 2015 under Prime Minister Najib Abdul Razak based on a similar charge.

Khairuddin questioned Munir's place for demanding an apology when the two men - Anwar and Mahathir - had no qualms meeting and shaking hands.

"I would also like to advise this Amanah Youth vice-chief to be more mature in politics.

"If Munir is bankrupt of ideas in politics, he should sit quietly and just follow the lead of the top leaders who helm the opposition in a pragmatic manner to ensure Harapan captures Putrajaya in the next general election," he said.