Thirty Turkish war planes on Thursday carried out a new wave of bombings against targets of the Kurdistan Workers Party (PKK) in northern Iraq, the NTV and CNN-Turk channels reported.

The F-16 planes struck five locations in northern Iraq, hitting shelters, storage points, caves, and depots of the PKK in retaliation for a deadly attack that killed three Turkish troops earlier.

The co-leader of Turkey's main Kurdish party on Thursday dismissed air strikes and police raids by Ankara against Islamic State (IS) jihadists as a "show", saying their real target was Kurdish militants.

In an interview with Agence France-Presse, Selahattin Demirtas of the Peoples' Democratic Party (HDP) said the peace process between Turkey and Kurdish militants was now "in deep crisis" due to the offensive by Ankara against the separatist rebels but insisted it should not be written off.

Pointing to a crater left by one of scores of Turkish air strikes in Iraq's Kurdistan region, a PKK rebel official said that "Turkey has declared war against us".

For three decades, Turkey was at war with the Kurdistan Workers Party (PKK), which was seeking an independent state in southeastern Anatolia.

Five people died Thursday in new attacks on the Turkish security forces blamed on Kurdish militants, as Ankara stepped up its controversial campaign against the separatist rebels.

A new wave of violence included the killing of three Turkish troops that the army said was carried out by Kurdistan Workers' Party (PKK) militants, the deadliest such attack on the security forces since the crisis began last week.

Turkey's allies know it is playing a double game with its twin onslaught against Kurdish rebels and the Islamic State group, but are turning a blind eye to keep NATO's only Muslim member on side, analysts said.

The very public show of solidarity for Turkey's fight against "terrorism" at an emergency NATO meeting on Tuesday hid the discomfort some allies feel about President Recep Tayyip Erdogan's strategy.

German Foreign Minister Frank-Walter Steinmeier and Iraqi Kurdish President Massud Barzani have agreed that Turkey must continue the Kurdish peace process despite escalating violence, Berlin said Wednesday.

Turkey has launched military strikes against Kurdistan Workers' Party (PKK) militants in Turkey and northern Iraq, as well as against Islamic State jihadists in Iraq and Syria, following attacks it blames on the two groups.

Syria's foreign ministry said Wednesday it was skeptical about Turkish efforts to fight the Islamic State group, in its first official reaction since Ankara began air strikes against the jihadists.

"It is better late than never, but are Turkish intentions to fight the terrorists of Daesh (IS), al-Nusra Front, and al-Qaida-linked groups genuine?" the ministry asked in a letter to the United Nations.

Turkish warplanes on Wednesday pounded targets of PKK militants in northern Iraq, as parliament was to meet in emergency session to debate the government's controversial campaign against Kurdish rebels and jihadists.

Turkey's military campaign -- which the government says was it was forced to carry out after a series of attacks blamed on Islamic State (IS) jihadists and Kurdistan Workers Party (PKK) militants -- has inflamed tensions in Turkey after its inconclusive June elections. 

Turkish President Recep Tayyip Erdogan met his Chinese counterpart Xi Jinping for talks in Beijing on Wednesday, a day after securing NATO's backing for Ankara's fight against Islamic State militants.

Ankara is expanding a cross-border campaign against the Islamic State group in Syria, and also attacking positions of the outlawed Kurdistan Workers' Party in northern Iraq after deadly attacks inside Turkey.

Turkish jets on Tuesday hit Kurdish militants in southeastern Turkey after the group fired on security forces, the army said.

"Two F-16 jets carried out air strikes at 1510 local time (1210 GMT) against the terrorist group" in a mountainous region bordering Iraq, the army said in a statement, referring to the outlawed Kurdistan Workers' Party (PKK).