Col. Kumar Lama was visiting his wife in St. Leonards-on-Sea in East Sussex when he was picked up by London's Metropolitan Police, Republica reported. He is deployed with a Nepalese detachment as part of the U.N. peacekeeping operation in Sudan.
The Nepalese government lodged a formal protest with John Tucknot, the British ambassador in Kathmandu.
Scotland Yard issued a statement after Thursday's arrest that said Lama is suspected of torture in 2005 during the decade-long civil war in Nepal, The Guardian reported. The complaint was filed by the Advocacy Forum, a Nepalese human rights group, on behalf of an alleged victim.
The forum said police had been given supporting evidence. The Scotland Yard statement said investigators with the counter-terrorism unit would determine if there is enough evidence to present a case to the Crown Prosecution Service.
The case could be tried in Britain.
"This arrest has brought a ray of hope to victims," Mandira Sharma, the forum's founder, said.