Turkey on Monday said it had summoned the U.S. charge d'affaires in Ankara to demand an explanation over a leak by Edward Snowden that Washington has spied intensively on Turkish leaders since 2006.

Der Spiegel reported that as well as sharing intelligence with NATO partner Turkey, the United States and its ally Britain have been conducting extensive electronic surveillance on the Turkish leadership.

Turkish authorities on Monday detained some two dozen police officers in new nationwide raids over an alleged plot to overthrow the Islamic-rooted government of President Recep Tayyip Erdogan.

Police conducted early morning raids in 16 cities across Turkey, including Istanbul as well as the western province of Izmir, and detained at least 20 police officers, private NTV television reported.

Turkey's army chief has warned that the army will do whatever is necessary if its "red lines" are not respected in peace talks with Kurdish rebels.

His comments came amid intensified efforts by the government to restart stalled peace talks with the Kurdistan Worker's Party (PKK), which launched an insurgency seeking self-rule in the southeast in 1984. 

Cengiz, a street seller who plies his trade selling bread rings in the center of Istanbul, is usually a fervent supporter of Turkey's newly-elected President Recep Tayyip Erdogan. But on one issue, he begs to differ.

"I support Erdogan. But I must say he made one error and that's to allow the Syrians into our country," he said.

The number of refugees from Iraq's Yazidi religious minority who have fled to Turkey from the advance of jihadists has risen to 16,000 and may rise further, a top provincial official was quoted as saying Saturday.

The number marks a sharp rise from the figures of several thousand previously given and shows Turkey is dealing with another major influx of refugees as it gives sanctuary to some 1.2 million fleeing the Syria conflict.

Kurdish groups from Iraq and three neighbouring countries are putting aside old rivalries to battle jihadist militants, but there are cracks in this newly-forged unity and it may not last.

Mevlut Cavusoglu, who was on Friday named as the new Turkish foreign minister, is a strong supporter of Turkey's integration with the European Union as well as part of the inner circle of President Recep Tayyip Erdogan.

Cavusoglu takes on the post at a critical time, facing an enormous task with Turkey mired in foreign policy difficulties in the Middle East amid the strife in its conflict-torn neighbors Syria and Iraq.

Turkish President Recep Tayyip Erdogan on Friday approved a new cabinet stacked with loyal allies just a day after he became head of state, with former Europe minister Mevlut Cavusoglu promoted to foreign minister.

Prime Minister Ahmet Davutoglu, who took over Erdogan's former job as prime minister on Thursday, announced a ministerial line-up little changed from Erdogan's cabinet, with only four new names.

The number of refugees from the Syria conflict now tops three million, the U.N. said Friday, as U.S. President Barack Obama admitted he has no strategy to tackle advancing jihadists.

In Geneva, U.N. refugee agency chief Antonio Guterres said Syria had become the "biggest humanitarian emergency of our era" after a million people joined the exodus in the past year alone.

Recep Tayyip Erdogan, who was sworn in as Turkey's president Thursday, climbed from a humble youth in Istanbul to become one of the most significant but controversial leaders in the Islamic world.

Erdogan, who served as premier since 2003, is lauded by his supporters as a transformative figure who modernized Turkey and delivered power back to the people from the secular and military elite.