Syria’s al-Qaida affiliate overran bases belonging to a Western-backed rebel group near the northern city of Aleppo after heavy clashes that killed at least 20 fighters, activists said Saturday.

The fighting took place near the town of Atarib some 30 kilometers (18 miles) west of Aleppo, and pitted the al-Qaida-linked Nusra Front against the mainstream Hazm Movement, which has received support from the United States.

The Britain-based Syrian Observatory for Human Rights said Nusra Front fighters seized control of several Hazm bases. At least 29 Hazm fighters and six Nusra Front militants were killed in the clashes, it said. […]