Turkish Prime Minister Recep Tayyip Erdogan on Friday hit back at critics who wrote an open letter published in British daily The Times blasting his handling of the civil unrest which engulfed Turkey last month.

"Treating our government as 'dictatorial' only shows impertinence...," Erdogan told reporters in Istanbul, referring to the letter.

Turkey sent a new signal of pressures squeezing its economy on Wednesday, warning it may cut the growth outlook a day after a juggling act with interest rates to shore up the lira.

The moves came just a week after Prime Minister Recep Tayyip Erdogan sought to reassure investors that their capital was safe in Turkey, where weeks of deadly protests had posed the biggest challenge faced by the Islamic-rooted government during its decade-long rule.

A 16-year-old Turk died Thursday after being hit in the head by a stray bullet from clashes across the border in war-torn Syria, hospital sources said, the second such death on the Turkish side this month.

Ahmet Gunduz died in hospital in the capital Ankara after being struck by gunfire on July 16 in the small southeastern town of Ceylanpinar, which lies across the border from the northern Syrian town of Ras al-Ain.

The United States on Wednesday blacklisted an operative with the radical Marxist group which claimed the suicide bombing of the U.S. embassy in Ankara earlier this year in which one person died.

Bulut Yayla was designated a terrorist under a State Department order, while the listing of the outlawed Revolutionary People's Liberation Front (DHKP-C) was also reviewed and Washington decided to keep up its designation as a foreign terrorist organization.

A Turkish court on Monday overturned a judgement suspending the redevelopment of Istanbul's Gezi Park, the issue that sparked huge anti-government protests last month.

The regional administrative court reversed a May 31 decision by an Istanbul court to halt redevelopment work at the park, press agency Dogan reported.

Nuray and Ozgur fell in love behind the barricades of last month's mass anti-government protests in Istanbul, and their wedding ceremony would have been incomplete without the Turkish police.

So when the couple picked the epicenter of the revolt on Taksim Square as the venue to tie the knot Saturday, the anti-riot police obliged and provided the water cannon.

Turkey on Friday vowed to "respond immediately" to any violation of its borders by Kurdish separatists fighting in Syria.

Foreign Minister Ahmet Davutoglu made the warning following the seizure of a Syrian town on the border with Turkey by rebels from the Kurdish Democratic Union Party, a Syrian branch of the outlawed Kurdistan Workers' Party (PKK).

Rebels from the banned Kurdistan Workers' Party (PKK) on Friday accused Ankara of deliberately derailing a fragile peace process designed to end nearly three decades of conflict.

"It is clear that the government is behind efforts to sabotage the peace process," said a PKK statement reported by Kurdish news agency Firat.

Turkish Prime Minister Recep Tayyip Erdogan has refused to speak to Egypt's new Vice-President Mohammed ElBaradei, the latest broadside in a spat that erupted after the military coup in the Arab world's most populous country.

Erdogan infuriated Egypt's interim leaders after he voiced support for ousted Islamist president Mohammed Morsi.

A 17-year-old Turk died of his injuries in a southeastern town on Wednesday after being hit by stray gunfire coming across the border from war-torn Syria, Turkish media reported.

Mahsun Ertugrul died in hospital after receiving a gunshot to the chest in the small Turkish border town of Ceylanpinar on Tuesday, Dogan news agency said.