Amnesty International has accused Kurdish authorities of forcibly displacing Arabs from their homes in some parts of Syria. Earlier, Kurdish fighters announced an alliance with Arab fighters.
The London-based group said a fact finding mission that visited 14 towns and villages in northern and northeastern parts of the country had uncovered a "wave of forced displacement and home demolitions amounting to war crimes carried out by the Autonomous Administration."
"By deliberately demolishing civilian homes, in some cases razing and burning entire villages, displacing their inhabitants with no justifiable military grounds, the Autonomous Administration is abusing its authority and brazenly flouting international humanitarian law," said Lama Fakih, Amnesty's senior crisis adviser.
Some civilians said they were threatened with US-led coalition airstrikes if they failed to leave, Amnesty said.
Strong presence against 'IS'
Syrian government forces withdrew from mainly Kurdish areas in 2012, with the Kurdish-led Autonomous Administration left to fill the void. Its security forces, which include the Kurdish People's Protection Units (YPG), have proved effective in fighting "Islamic State" ("IS"), carving out an autonomous zone for itself in northern Syria and advancing into IS-held areas towards Raqqa.
However, residents of the central Raqqa and the northeastern Hasakeh provinces told Amnesty that the Kurdish fighters had used the pretext of their battle with IS to destroy mainly Arab homes.
Amnesty identified "a deliberate, coordinated campaign of collective punishment of civilians in villages previously captured by IS, or where a small minority were suspected of supporting the group."
The rights watchdog went on to cite Kurdish fighters as saying the forced displacement targeted IS sympathizers, including Kurds, and was, in some cases, for the residents' own security.
Arms dropped as new alliance formed
Earlier, the Kurdish YPG militia announced a new alliance with small groups of Arab fighters also battling IS. The YPG, which has made gains with the help of US air power, forms the largest part of the alliance, with the other groups referring to themselves as the Syrian Arab Coalition.
US forces on Monday made an airdrop, believed to have contained small arms ammunition and other supplies, as part of a revamped strategy.
Arab rebels in the alliance said they had been informed by Washington head of the airdrop that new weapons were on their way that would help them launch a joint offensive with the Kurds against IS in its de-facto capital of Raqqa.
The US military has confirmed only dropping supplies to "vetted" opposition fighters, but would say no more about the groups or the equipment in the airdrop.
Washington has said it could direct funding and weapons to Arab commanders working with the YPG.
rc/kms (AP, AFP dpa, Reuters)