Nairobi - Military courts in war-torn Somalia are guilty of a raft of abuses and are used by the internationally-backed government to jail hundreds without fair trial, Human Rights Watch said on Wednesday.
The courts "have tried hundreds of people beyond the courts' legal mandate, or in proceedings that fall short of international fair trial standards", the US-based HRW said in report.
Over a dozen people convicted last year were sentenced to death and executed, "magnifying the harm to basic rights", the report added.
"Summary trials by Somalia's military courts may be convenient for the Somali authorities, but that can't justify violating the rights of defendants," said HRW's Leslie Lefkow, adding civil cases must not be heard in military courts.
The fragile government is struggling to impose its authority over a land ravaged by over two decades of war, with a UN-mandated African Union force fighting alongside the army to capture territory from al-Qaeda-linked Shabaab insurgents.
International donors have poured billions of dollars into Somalia to support the government and as aid, as well as to fund the military force battling the Islamist Shabaab.
But HRW warned the government was failing to abide by basic standards of human rights.
"We received several credible reports of defendants being mistreated," the report added, quoting relatives of those they said had been beaten with sticks and wires.
The report was based on interviews with over 30 defendants as well as key court officials, "despite very real concerns of reprisals", HRW added.
Those interviewed by HRW said the courts would not accept criticism.
"These military tribunal guys think they have absolute power, and you can't talk to them," one defence lawyer said.
"You can't ask them anything, and they don't respect the human rights of people."
A relative of a government official sentenced to death last year for allegedly murdering his wife said that no evidence was brought to the court against him.
"There was not a single witness, there was no gun," the relative told HRW.