Former Sabah chief minister Musa Aman has finally returned to Malaysia, according to the Immigration Department.

In a statement, the department’s director-general Mustafar Ali said the aircraft carrying Musa and his delegation arrived at the Sultan Abdul Aziz Shah Airport, Subang from Seletar Airport, Singapore at about 6.45pm today.

Musa and other passengers on the aircraft underwent immigration checks upon arrival, which were completed at about 7pm.

“However, Musa could not present himself to the immigration counter due to health reasons.

"The passengers’ documents had been checked and recorded in the Immigration Department’s computer system,” the statement read.

Mustafar said that the police and MACC investigators have been notified of the ex-chief minister's arrival.

Earlier today, Bernama quoted Musa's former political secretary, Joh Wid, as saying that he had been undergoing treatment at the Clementine Churchill Hospital in London following a heart bypass surgery.

He was then referred to the Mount Elizabeth Hospital in Singapore for follow-up treatment before returning to Malaysia.

Police are investigating Musa for allegedly intimidating Sabah governor Juhar Mahiruddin soon after the 14th general election, which the former denies.

The MACC, meanwhile, is reportedly investigating him for an alleged attempting to buy off state assemblypersons following the election.

He had left the country on May 16.

It is understood that he returned from Singapore via a medical evacuation aircraft.

Meanwhile, Musa’s aide Awang Faisal said the ex-chief minister is currently being examined by doctors at a local hospital and will soon address “all outstanding issues.”

“He has given his full cooperation to the authorities, and will continue to do so despite health concerns and against his doctor’s advice in order to attend to his obligations.

“On behalf of Musa, I wish to thank all well-wishers who have prayed for his speedy recovery,” he said.