PAS president Abdul Hadi Awang said he is prepared to resign as vice-president of the International Union of Muslim Scholars (IUMS) after receiving flak from the union for his visit to Teheran.

"I have written a letter (of explanation) and am prepared to resign.

"I'm holding the position not because I asked for it but I was appointed," Hadi is quoted as saying in an Utusan Malaysia report.

PAS has often used Hadi's position in IUMS to bolster his credentials as an Islamic leader but he came under criticism from the union for attending an international conference in Teheran last Saturday.

The union, in a statement released in the name of IUMS president Yusuf al-Qaradawi, criticised the timing of Hadi's visit when the Iran-backed Syrian regime was carrying out a crackdown on rebels in Aleppo.

However, Hadi questioned whether the statement really came from Yusuf, an internationally renowned Islamic cleric.

"He (Yusuf) is sickly, so I do not know whether the statement really came from him or if it came from someone else," he is quoted as saying.

In a statement issued in Arabic on Tuesday, the union condemned Hadi for attending the conference in Teheran, at which Iran's Supreme Leader Ayatollah Ali Khameinei delivered the closing speech.

"The International Union of Islamic Scholars is puzzled by the timing of the visit, at a time when Iran is brutally killing our brethren, particularly in Aleppo and Syria as a whole.

"The union also condemns the unsanctioned visit by one of our leaders and it does not represent anyone but the individual himself.

"The union also awaits Hadi's explanation over his visit, for which time and place were not endorsed," IUMS said in a Facebook post.

Meanwhile Malay rights NGO Perkasa chief Ibrahim Ali hopes that Hadi's Teheran visit has more meat to it than just a glamour trip.

"What use is it? If it benefits us, then it is worth it. But if he went there just for glamour, then the PAS president's visit is self-effacing, like a celebrity who has vanity pictures shot but it means nothing. It's a waste if so," Ibrahim said at a press conference in Kuala Lumpur.

Commenting further, he said Hadi's visit to Iran may have negative connotations, since the country is involved in the ongoing bloodshed in Aleppo, Syria.

However, Ibrahim said, the conference Hadi attended showed something positive as it united both Sunni and Shiite Muslims.