Switzerland's first full trial of crimes against humanity concluded this week, with the defendant, a former Gambian minister accused of rape and murder, giving a defiant closing speech in which he claimed to be a victim of racism and lies.

Ousman Sonko, a former interior minister of Gambia under ousted dictator Yahya Jammeh, is the highest-ranking official ever to be tried in Europe using universal jurisdiction which allows the most serious crimes to be prosecuted anywhere.

During the trial in Switzerland's Federal Criminal Court in Bellinzona, the court heard details of the charges of rape, torture and murder allegedly committed between 2000-2016 either by Sonko or under his watch.

"I regret that they (the plaintiffs) discredited themselves in this way by lying, with the sole aim of supporting the accusation against me, in defiance of the truth," Sonko, 55, said in closing remarks before the court late on Thursday.

He also denounced his seven-year pre-trial detention - a period which he said was spent in solitary confinement and affected his health. Sonko told the court it was "part of a history of colonialism and racism".

"My country does not need expiatory victims immolated before foreign judges," he said.

There was no immediate response to his allegations from the Swiss federal justice department or from the Attorney General.

Landlocked Switzerland never had an empire but its banks and authorities benefited from colonialism, and systemic racism persists in Switzerland, a UN-mandated report said in 2022.

Benoit Meystre, a legal adviser at campaign group TRIAL international, which filed the complaint against Sonko, said he found the ex-minister's closing speech "disturbing".

"He was pretty disrespectful towards Gambians as he was positioning himself as the victim," he said.

TEARS AND HEAVY SILENCES

Sonko fell out with Jammeh in the final months of his 22-year repressive rule before the latter was forced to flee in January 2017 after an election defeat. That same month, Sonko was arrested in Switzerland while seeking asylum.

Switzerland's public prosecutor is seeking the maximum penalty of life imprisonment.

Witnesses described the trial as emotional, with testimony punctuated by heavy silences and occasional tears.

One of the plaintiffs, Binta Jamba, told the court she was raped multiple times by Sonko after he murdered her husband. The court removed the defendant to a side room during her testimony. Sonko said he was abroad when the alleged rapes occurred.

Her lawyer Annina Mullis, who is acting for several plaintiffs, voiced confidence they had built a strong case.

"The defence still could not explain many of the contradictions between the defendant's declarations and the facts established," she told Reuters.

No date for a verdict has yet been given.