Former prime minister Dr Mahathir Mohamad should not mix matters of religion with politics, National Fatwa Council chairperson Abdul Shukor Husin says.

He said this in reference to Mahathir's criticism of religious leaders who defended the haj pilgrimage sponsored by 1MDB.

"We respect Mahathir as a statesman, but he should not mix matters of religion with political agenda because when they are put together, everyone becomes embroiled," Shukir is quoted as saying by Utusan Malaysia today.

Mahathir had claimed that the haj pilgrimage sponsored with "tainted" 1MDB funds was not accepted by God (mabrur).

Several mufti, including those from Kelantan and Pahang, later rebutted the former prime minister.

Shukor said the opinions of the mufti were formed based on scholarly sources.

"They are not their personal opinions," he said.

He added that the mufti also were not always in agreement with the government.

"That is why, prior to this, the mufti have criticised issues of apostasy, entertainment concerts and Zika virus, even though it was not in line with the government," Shukor is quoted as saying.

1MDB is in the process of being wound up after becoming embroiled in an international money laundering scandal and is the subject of investigation in several countries including, the United States, Switzerland, Singapore and the United Arab Emirates.

At its peak, the government fund had a debt of around RM50 billion.