British police have charged a serving colonel in the Nepalese army with two counts of torture allegedly committed during the Himalayan nation's civil war in 2005.
Britain's Metropolitan Police said on Friday that Kumar Lama, 46, had been arrested at a residential address in the English town of St. Leonards-on-Sea, about 115km southeast of London, on Thursday.
The charges relate to two separate incidents that allegedly occurred between April 15 and May 1, 2005, at the Gorusinghe Army Barracks in Nepal.
Lama is charged with intentionally "inflicting severe pain or suffering" on two separate individuals as a public official - or person acting in official capacity.
He will appear at London's Westminster Magistrates' Court on Saturday, police added.
It was not immediately clear what Lama was doing in Britain.
But UK authorities claim "universal jurisdiction" over serious offences such as war crimes, torture, and hostage-taking, meaning such crimes can be prosecuted in Britain regardless of where they occurred.
Meanwhile, Nepal's government summoned the British ambassador on Friday to call for the immediate release of the colonel.
"We express strong objection to this mistake and urge that it be corrected ... and Lama be released," Shrestha told reporters in Kathmandu.
Human Rights Watch said the arrest sent a warning to those accused of serious crimes that they cannot hide from the law forever.
"The UK's move to arrest a Nepali army officer for torture during Nepal's brutal civil war is an important step in enforcing the UN Convention against Torture," Brad Adams, Asia director of Human Rights Watch, said in a statement
Rights groups accuse both the security forces and former Maoist rebels of committing abuses including torture during the decade-long conflict which killed more than 16,000 people.
The Maoists ended the conflict in 2006 under a peace deal with the government, won elections four years ago and are now heading a coalition ruling the young Himalayan republic.