BEIRUT: A Kurdish man tortured by rebels in northern Syria has died of his wounds on Monday, a watchdog said, noting that some armed groups have taken up methods used by the regime of President Bashar al-Assad.

Khaled Bahjat Hamdu, 37, was captured on Friday along with scores of other Kurds in the northern Syrian province of Aleppo, near the village of Hayan, said the Britain-based Syrian Observatory for Human Rights reported.

Hamdu "died from wounds caused by torture inflicted on him while he was captured by an armed group near the village of Hayan," it said.

"He was tortured using electricity. He was one of 120 captives released on Sunday, but he was so weak that the following morning, he died," said Observatory director Rami Abdel Rahman.

"Some of the armed groups are using the regime's methods of repression," said Abdel Rahman. "We should not be silent about this."

Syrian rebels clashed with Kurdish militia in Aleppo on Friday, leaving 30 dead whole more than 200 were captured, the Observatory said.

The Observatory relies on a countrywide network of activists and medics in civilian and military hospitals. It says its tolls take into account civilian, military, and rebel casualties.

Abdel Rahman said the area northwest of Aleppo is home to some 600,000 Kurds, and that there are fears that communal tensions may grow in areas near the Turkish border.

"In areas where rebels have forced the regime out, there is a security vacuum. Some of the fighters don't want democracy at all, they're just warlords who are taking advantage of the chaos," said Abdel Rahman.

The head of a UN commission investigating rights abuses in Syria said in September that both sides to the conflict were to blame for gross violations of human rights.

"Gross violations of human rights have grown in number, in pace and in scale," Paulo Sergio Pinheiro said in mid-September, adding that President Bashar al-Assad's regime -- and the rebels, to a lesser extent -- had committed war crimes.