By Panarat Thepgumpanat and Patpicha Tanakasempipat
BANGKOK (Reuters) - A Thai soldier was charged on Tuesday with murdering a youth activist from an ethnic minority in an anti-drugs operation, police said, a case that has sparked concern among rights groups which have called for an independent investigation.
Human Rights Watch said army officers had used anti-drug operations in the past as a cover for attacks on activists who exposed official wrongdoing or defended minority rights.
Chaiyaphum Pa-sae, a 17-year-old advocate for the rights of ethnic Lahu and other vulnerable ethnic minorities in northern Thailand, was shot on Friday.
The soldier turned himself in to police on Tuesday and was charged with murder, said Police Colonel Chonlathep Maichai, of Chiang Dao district police station in the ancient walled city of Chiang Mai.
"We'll give justice to both sides," Chonlathep told Reuters.
An army incident report said soldiers found 2,800 methamphetamine pills in a car in which Chaiyaphum and his friend were driving. The two were taken into custody, but Chaiyaphum ran away and was about to throw a grenade at the officers, prompting the soldier to shoot, it said.
Army spokesman Colonel Winthai Suvaree told reporters the soldier shot in self-defence.
"We'll prove whether Chaiyaphum's killing, committed by the authorities, was justified by law," defence lawyer Sumitchai Hattasan told Reuters.
The Thai army has previously been criticized by rights groups for enforced disappearances of human rights defenders.
Amnesty International called on the government to "immediately order an independent, impartial and effective investigation into the killing" in a statement on Tuesday.
Human Rights Watch also called for a thorough investigation.
"Ethnic minorities in Thailand will never have full equality so long as those acting on their behalf face grave risks every day and killings such as this are not investigated properly," said Asia director Brad Adams.
(Editing by Nick Macfie)