President Recep Tayyip Erdogan on Tuesday vowed that Turkey would press on with its relentless campaign against Kurdish militants "until not one terrorist" was left, as Ankara launched new air strikes against the rebels.

Turkey is currently pressing a two-pronged "anti-terror" offensive against Islamic State (IS) jihadists in Syria and PKK militants in northern Iraq and the southeast following a wave of attacks.

But, so far, the air strikes have overwhelmingly concentrated on the separatist Kurdish rebels, who have responded by tearing up a 2013 ceasefire and waging a bloody campaign against the security forces.

"We will continue our fight until weapons are laid down... and not one single terrorist remains within our borders," Erdogan said in a televised speech in Ankara.

He said the weapons of the PKK and other militant groups must be buried "under concrete" to show they were no longer a threat to the Turkish state.

"I'm not talking about laying down arms, I'm talking about burying them. I'd like to emphasise this," Erdogan said.

Turkish warplanes overnight staged a fresh wave of attacks on Kurdish militant targets following a day of bloody attacks that killed six members of the security forces.

The overnight strikes hit 17 PKK targets in the southeastern province of Hakkari, destroying them all, the army said.

On Monday, four Turkish police officers were killed in a roadside bombing in the southeastern province of Sirnak while a Turkish soldier was killed in a rocket attack on a military helicopter.

Meanwhile, in Istanbul a senior police officer in charge of the city's bomb disposal department was killed in clashes that followed a pre-dawn suicide bombing.

The PKK Tuesday claimed that attack, confirming that three of its militants had been killed including a suicide bomber and dismissing claims a smaller leftist group had been behind the strike.

In new violence overnight, a Turkish soldier was killed in a gun attack on a military post in Sirnak, also blamed on the PKK.

Two Turkish F-16s then Tuesday afternoon destroyed PKK targets in Sirnak province, the army said.

According to an AFP toll, 29 members of the security forces have been killed in violence linked to the PKK since the current crisis began.

- 'Serious losses' -

The European Union and United States, which like Turkey list the PKK as a terror group, have backed Ankara's right to strike against the militants but also indicated concern about the scale of the campaign.

State Department Spokesman John Kirby said Ankara should "take the necessary steps to prevent any civilian casualties and to act in accordance with international humanitarian law."

The state-run Anatolia news agency reported over the weekend that so far 390 "terrorists" had been killed in the campaign against the PKK.

Erdogan said that the over two-week air campaign against the PKK had already inflicted "serious losses" on the group.

But even such an intense campaign may not be enough to finish the PKK.

"Turkey's air campaign damages the PKK, but is not sufficient to destroy it," said Pinar Elman, Turkey analyst at the Polish Institute of International Affairs (PISM).

"The decades-old conflict has shown that military means are not sufficient to fight against the terrorist group, and political reforms are necessary," she told AFP.

The Marxist-inspired PKK has waged a three decade insurgency since 1984 for greater autonomy for Turkey's Kurds that has left tens of thousands dead.

Erdogan also declared the peace process to end the PKK insurgency is currently "on ice."

"This is a familiar lose-lose dynamic," said Nigar Goksel of the International Crisis Group (ICG)

"Neither the Turkish state nor PKK can win by military means. For both, the price of their war is potentially higher than ever," she said in a briefing note.

- 'Terrorist is a terrorist' -

Ankara has also vowed to begin strikes in the next days against IS jihadists in Syria alongside US forces who have now started arriving to use the well-located Incirlik air base in southern Turkey.

Washington has long been pushing its NATO ally Turkey to step up the fight against IS and Ankara's involvement in the coalition has been seen as a game-changing moment in the fight against IS.

Erdogan said "effective operations" were carried out against IS jihadists, saying the group also posed a threat to Turkish security.

"For us, there is no difference between terrorist organisations. Whatever their purpose is, for us, a terrorist organisation is a terrorist organisation," he said.