Captain Ammar al-Wawi, a spokesman for the 30th Division, said that the situation remained critical

A US attempt to relaunch its much-criticised rebel training programme faced a setback yesterday when a second batch of western-trained fighters were detained by other rebel groups in northern Syria.

About 70 fighters from the US-trained group, called the 30th Division, entered the Bab al-Salama border crossing north of Aleppo in a heavily armed convoy of 12 vehicles with US air cover, according to the Syrian Observatory for Human Rights.

However, they faced “problems” from the Islamist Shamiya Front, a Turkish-backed rebel coalition operating against Isis around Aleppo, according to the US-trained rebels.

A spokesman for the Shamiya Front said that it had detained members of 30th Division, but only temporarily. He added that fighters from the group had been in possession of Syrian regime