United Nations appeals judges on Wednesday expanded the jail terms of two spy chiefs of late Serbian President Slobodan Milosevic who had been convicted of war crimes committed amid the breakup of Yugoslavia.

The court sentenced former state security service chief Jovica Stanisic and deputy Franko Simatovic to 15 years in prison, adding three years to a previous conviction from 2021.

The two men were convicted over their role in supporting Bosnian Serb paramilitaries that engaged in a campaign of ethnic cleansing in parts of Bosnia and Croatia.

The UN court found Stanisic and Simatovic "shared the intent to further the common criminal plan to forcibly and permanently remove the majority of non-Serbs from large areas of Croatia and Bosnia," judge Graciela Gatti Santana said.

"This pronouncement marks a milestone in the mechanism's history... The appeals chamber pronounces the last appeal judgment," she said.

The sentence was delivered by the UN's International Residual Mechanism for Criminal Tribunals (IRMCT), which took over the remaining war crimes cases related to Yugoslavia in 2017.

What else do we know about the proceedings?

The pair had appealed the convictions for the war crime of murder and the crimes against humanity of murder, persecution, forcible transfer and deportation.

Prosecutors had appealed against their acquittal on several other charges and asked for a longer sentence, which was then heeded by the court.

The two spy chiefs had been acquitted in 2013 after it was found that there was not enough evidence to link them to the actions of Bosnian Serb paramilitaries.

A retrial was ordered in 2015, and the pair was convicted six years later of training and financing Serb forces that took over the northern Bosnian town of Samac in 1992.

Judges in 2021 said that Serb forces launched a "campaign of terror" against Bosniaks and Croats in the area that included killings, rapes, looting and the destruction of Islamic and Catholic religious buildings.

Non-Serbs were also held in six detention centers where various abuses were committed.

Last Yusgoslav war trial

Stanisic and Simatovic's appeal was the final case in war crime prosecutions over the conflict in the western Balkans in the 1990s.

Milosevic was put on trial for alleged war crimes committed during the breakup of Yugoslavia, but died in his jail cell in 2006 before a verdict was reached.

Bosnian Serb general Ratko Mladic lost his final appeal against a life sentence in 2021, and political leader Radovan Karadzic was convicted of genocide and sentenced to life in prison in 2016.

sdi/msh (Reuters, AFP, AP, dpa)