ABUJA, Nigeria (AP) — Nigeria’s highest judicial officer has resigned, an aide said Monday, a week after the country’s Supreme Court justices accused the top-ranking judge of corruption. Justice Tanko Muhammad denies the allegations.

Justice Muhammad resigned as the Chief Justice of Nigeria on Sunday night, his spokesperson told The Associated Press. But he didn’t provide an explanation for his decision, though local Channels Television cited health reasons, quoting unnamed sources.

The 68-year-old was appointed Nigeria’s chief justice in July 2019, replacing Walter Onnoghen who was prosecuted on corruption charges.

Muhammad’s resignation comes a week after 14 Supreme Court judges drafted a rare letter accusing him of graft.

The letter claimed that judges “were not accorded the privilege of travelling with accompanying persons as was the practice.” It also said the chief justice “totally ignored” the judges’ demand but travelled with his “spouse, children, and personal staff.”

The judges said that although the country’s National Assembly approved a budget increase for the Court, “we find it strange” that the “Court cannot cater for our legitimate entitlements. This is unacceptable!”

The new Chief Justice of Nigeria is expected to be announced and confirmed for office from among the Supreme Court judges in the coming days.