"But it came as the US was accused by Kurds of tolerating a renewed Turkish government assault on its Kurdish minority as the price for permission for US aircraft to use Turkey's Incirlik air base against Isis jihadists for the first time."

Kurdish guerrillas have killed two Turkish soldiers in an ambush in south-east Turkey as fighting resumes between Turkish security forces and Kurdish militants, ending a two-year-old ceasefire. The attack came after Turkish aircraft heavily bombed bases of the Kurdistan Workers Party (PKK) in the Qandil Mountains in northern Iraq.

In a sign that the PKK has resumed military operations against the government, a Turkish army vehicle on a road near Diyarbakir, the largest Kurdish city, was hit by bomb blasts followed by rifle fire, according to the army. A further four soldiers were wounded in the attack.

The attack came in response to a heavy air raid by Turkish aircraft on PKK bases in the Qandil Mountains in northern Iraq on Saturday – ostensibly part of a new Turkish offensive against terrorist groups, said also to be aimed at Isis.

But it came as the US was accused by Kurds of tolerating a renewed Turkish government assault on its Kurdish minority as the price for permission for US aircraft to use Turkey's Incirlik air base against Isis jihadists for the first time.

"The Americans are not very clever in calculating this sort of thing," said Kamran Karadaghi, an Iraqi Kurdish commentator and former chief of staff to the Iraqi President, Jalal Talabani. "Maybe they calculate that with Turkey involved on their side, they don't need the Kurds."

The US denies giving the go-ahead for Turkish attacks on the PKK in return for American use of Turkish air bases, or of any link with Turkish action against Isis fighters and volunteers, who were previously able to move fairly freely across Turkey's 550-mile border with Syria.