Malaysia's two most senior judges have resigned from their posts, as Prime Minister Mahathir Mohamad's government purges top officials seen close to the previous administration.

The list of top officials who have either been removed from or quit their posts has steadily grown over the past month, after Mahathir's opposition coalition scored a spectacular victory in a May 9 general election.

Chief Justice Raus Sharif and Court of Appeal President Zulkefli Ahmad Makinudin will step down from their posts on July 31, according to a statement issued by the chief registrar's office of the federal court.

"His Majesty the King had given his assent to their resignation on June 8," the statement read.

Malaysia's legal fraternity had challenged the decision by the government of ousted Prime Minister Najib Razak to appoint Raus and Zulkefli last year, arguing that the two judges had already exceeded the retirement age.

Last week, Malaysia appointed a new attorney-general who said there would be "no cover ups" and that he would pursue criminal and civil action over a graft scandal at state fund 1Malaysia Development Berhad ( 1MDB ) which was founded by Najib.

The new attorney-general, Tommy Thomas, was brought in to replace Mohamed Apandi Ali, who in 2016 cleared Najib of any wrongdoing in the multi-billion dollar 1MDB scandal.

Najib has denied any wrongdoing in the case.

Central bank governor Muhammad Ibrahim also resigned last week, just two years into his five-year term.

Muhammad's exit is seen as a fallout from the 1MDB scandal, after the finance ministry said last month that about $500 million raised from a land sale by the government to the central bank was used to pay 1MDB's liabilities last year.