Geneva - Switzerland on Thursday detained former Gambian interior minister Ousman Sonko, who is accused of committing grave abuses under the regime of ousted president Yahya Jammeh.The arrest, confirmed by Swiss prosecutors, comes as The Gambia prepared to welcome their new president Adama Barrow, who had fled to Senegal after beating Jammeh in a landmark election that sparked a political crisis. Sonko had been one of Jammeh's top allies, serving in his presidential guard before leading the interior ministry from 2006 to 2016.Jammeh sacked him in September and Sanko fled to Sweden where his request for asylum was rejected. Sonko was detained in the Swiss capital Bern following a complaint filed by rights group TRIAL."He will be interrogated soon," Amael Gschwind, a spokesperson for Bern prosecutors told AFP, confirming the arrest. TRIAL, which campaigns for the Swiss judicial system to act on crimes committed abroad, described Sonko as one of Jammeh's "strongmen" and said he must have been aware of the violations committed under the fallen authoritarian regime. "Sonko could not have ignored the large-scale torture that political opponents, journalists and human rights defenders suffered", said Benedict de Moerloose of TRIAL's criminal law division. According to TRIAL, Sonko arrived in Switzerland in November and applied for asylum. It was not immediately clear where he had lived between his arrival and his arrest. TRIAL urged Switzerland to move forward with prosecution, suggesting it could give positive momentum to the unprecedented political developments underway in The Gambia. "The crimes of Jammeh's government have never been judged, and torturers walk free. At the time Gambia is preparing for a democratic transition, these developments send a strong message of hope," the rights group said in a statement. Jammeh refused to step down after his election loss to Barrow, but was ultimately forced to quit power and flee to Equatorial Guinea amid strong regional and international pressure. Residents of The Gambia, a country of roughly two million people, were anxiously awaiting Barrow's arrival which will cap the first-ever democratic transition of power in the nation's history.