The Inter-Parliamentary Union (IPU) of MPs from across the globe has called for jailed former opposition leader Anwar Ibrahim to be given the necessary medical treatment.

"Although the three-day IPU mission... acknowledged efforts in addressing Anwar’s health problems, it urged authorities to allow follow-up care requested by doctors in early June after he underwent hospital treatment," the union said in a statement.

IPU's three-day mission, which included a visit to Anwar in prison, concluded on Wednesday.

The call comes amid concerns about a tumour in Anwar's kidney.

A day before the IPU concluded its mission, Prime Minister Najib Abdul Razak also noted Anwar's condition, urging the relevant authorities to ensure he receives proper medical attention.

"I take note of Anwar's health and want the relevant authorities to ensure he receives the necessary treatment," Najib tweeted on Tuesday.

'Anwar isolated'

The IPU also expressed concern that Anwar is not allowed contact with other prisoners.

In addition, they urged that other charges against other MPs over Anwar's jailing to be dropped.

"The three-member delegation from IPU’s committee on the human rights of parliamentarians  also call for the dismissal of charges and investigations against eight opposition MPs, including Anwar’s daughter Nurul Izzah Anwar.

"Some of the MPs had taken part in demonstrations, while Nurul Izzah had been briefly arrested after criticising the judiciary during a speech in Parliament," it said.

It added the IPU delegation is urging Malaysian authorities to ratify and implement all key international human rights treaties.

It will present a full report on the mission to IPU members in October.