Ankara (AFP) - Turkish ground forces pounded Islamic State jihadists in Iraq and Syria after a suicide attack blamed on the extremists killed 10 German tourists, Prime Minister Ahmet Davutoglu said on Thursday, in a significant escalation of Ankara's fight against the group.

The intense shelling of some 500 IS positions on the Syrian border with Turkey and northern Iraq in just a 48-hour period following the attack on Istanbul's historic heart was the most serious Turkish assault against jihadist targets in recent times.

With Turkey beset by violence from Istanbul to its troubled southeast, six people, including three children, were killed in a devastating truck bomb attack on a police station in the southeastern Diyarbakir province blamed on Kurdish militants.

The outlawed Kurdistan Workers Party (PKK) is a arch foe of IS but the government has repeatedly insisted it makes no differentiation between the various "terrorist groups" it is fighting.

Speaking to Turkish ambassadors in Ankara at their annual meeting, Davutoglu said around 200 IS members were killed in the army's retaliation for the Istanbul attack. It was not possible to independently verify the toll.

"After the heinous attack in Istanbul, our armed forces hit in the last 48 hours some 500 positions of Daesh in Syria and Iraq with artillery and tank fire," Davutoglu said, using an Arabic acronym for IS.

"Every attack that targets Turkey's guests will be punished," he added.

- 'Vacate the border' -

Turkey has often been criticised by its Western allies for not doing enough to combat IS jihadists who have seized swathes of territory in Syria and Iraq.

But Ankara last year stepped up its involvement in the US-led coalition against IS, hosting American war planes at its Incirlik air base for deadly raids against the jihadists and conducting air strikes of its own.

The premier said Turkey was determined to dislodge IS jihadists fully from the Syrian border, which analysts says they have controlled for much of last year.

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"We will continue to fight the Daesh terror organisation in a determined way until it leaves the Turkish border area completely and as long as it behaves in a way that tarnishes the name of our holy religion Islam," he said.

Turkish authorities have identified the Istanbul suicide bomber as a 28-year-old Syrian who entered Turkey on January 5 along as an "ordinary migrant" fleeing the country's civil war. At the border, he was fingerprinted by migration authorities but never placed on any wanted list.

Turkey is currently hosting around 2.2 million refugees who have fled the fighting in Syria. Davutoglu warned against seeing all migrants as potential extremists, which he said would be playing into the hands of the "terrorists".

So far, a total of seven suspects have been arrested in connection with the bombing, Interior Minister Efkan Ala said on Thursday.

In addition, Turkish security forces rounded up over 70 suspected IS members across the country over the last few days, but it was not clear if any of them were directly connected to the Istanbul attack.

According to the Anatolia news agency, there are at least six Russian citizens among them.

Turkey was hit by three attacks blamed on IS in 2015, including a including a double suicide bombing in October in Ankara that killed 103 people, the country's worst-ever attack.

All those attacks targeted pro-Kurdish groups, who are vehemently opposed to IS. The attack on the German tourists, however, was the first time that foreign visitors have been targeted in the historic heart of Istanbul.

- 'Like an atomic bomb' -

Six people were killed, including three children, and 39 wounded in the car bomb that ripped through a police station in Cinar in Diyarbakir province and then caused an adjacent housing complex for officers' families to collapse, the local authorities said.

Security sources told AFP the victims killed in the building collapse included a five-month-old baby, a boy aged five and a girl aged one. Some 1.5 tonnes of explosives had been stuffed into truck.

"I thought it was an atomic bomb. It threw me to the ground," said Cinar resident Sitki Dinc.

The PKK launched an insurgency against the Turkish state in 1984, initially fighting for Kurdish independence although it now presses more for greater autonomy and rights for the country's largest ethnic minority.

The conflict has left tens of thousands of people dead.

A new upsurge of violence between the security forces and the PKK erupted in July following attacks blamed on Islamic extremists, shattering a fragile two-and-a-half-year truce.

So far, there has been no claim of responsibility for either the Istanbul attack or the Cinar bombing.