Prosecutors have urged UN war crimes judges to impose a 40-year jail term on a former Bosnian Croat politician, denouncing his initial 25-year sentence as inadequate for "massive" crimes committed in the Bosnian war.

In imposing its original sentence on Jadranko Prlic in 2013, "the chamber abused its discretion", prosecutor Barbara Goy told the International Criminal Tribunal for the former Yugoslavia on Tuesday.

"The crimes were massive in scale," she said. "Tens of thousands of Muslims were evicted from their homes ... Thousands were arrested and detained in awful conditions" during the 1992-1995 Bosnian war, she said.

OPINION: Commemorating Srebrenica

"Muslims were killed during attacks or when forced to work on the front lines. They were raped, they were sexually assaulted. Muslim houses and mosques were destroyed," said Goy.

In an appeal launched last week at the tribunal based in The Hague, Prlic, who denied all the charges, is seeking to overturn the 25-year jail term.

It was imposed after he was convicted of murdering and deporting Muslims during the conflict, which erupted as part of the wars that tore the Balkans apart and killed more than 100,000 people and left 2.2 million displaced.

After the war, Prlic served as the defence minister and foreign minister of the Federation of Bosnia and Herzegovina.

His five co-defendants in the case have also been sentenced to terms of 10 to 20 years in prison - which Goy slammed as "unreasonable".

'Croat domination'

Goy also called for 40 years in prison for three of the men: former Defence Minister Bruno Stojic and senior military officials Slobodan Praljak and Milivoj Petkovic.

They all "played key roles in the joint criminal enterprise to create Croat domination", Goy said.

Defence lawyer Michael Karnavas said the prosecution's appeal was "ludicrous".

"We do not accept the notion that Dr Prlic was ... involved in any capacity through any of those events," he said.

The appeals court is set to deliver its sentence in November as the special court winds down more than 20 years after it was set up to prosecute the worst crimes of the Balkans wars.

It has said the Prlic case is "one of the tribunal's largest and most complicated".

A total of 326 witnesses took the stand during a trial that opened in 2006. The first sentencing ran to more than 2,600 pages.

The special court is also due to deliver in November a highly anticipated sentence in the case of former Bosnian Serb military leader Ratko Mladic, the last person still on trial at the court.

In March 2016, the special court found former Bosnian Serb leader Radovan Karadzic guilty of genocide and he was sentenced to 40 years in prison.

The UN has set up another tribunal to deal with any cases not completely ended at the special court.