Mystery surrounds the surprise release of 49 Turkish diplomats and their families held captive for three months by ISIS. The Turkish government is denying any deal with the hostage-takers, making it unclear why ISIS, notorious for its cruelty and ruthlessness, should hand over its Turkish prisoners on Saturday, Sept 20 without a quid pro quo, foreign commentator Patrick Cockburn said in an article published at The Independent.

Hailed in Ankara as a triumph for Turkey, the freeing of the diplomats seized when Mosul fell to ISIS on 10 June raises fresh questions about the relationship between the Turkish government and ISIS. The Turkish President Recep Tayyip Erdogan says the release is the result of a covert operation by Turkish intelligence that must remain a secret.

He added on Sunday that “there are things we cannot talk about. To run the state is not like running a grocery store. We have to protect our sensitive issues; if you don’t there would be a price to pay.” Turkey denies that a ransom was paid or promises made to ISIS.

The freeing of the hostages comes at the same moment as 70,000 Syrian Kurds have fled across the border into Turkey to escape an ISIS offensive against the enclave of Kobani, also known as Ayn al-Arab, which has seen the capture of many villages.

The assault on Kobani is energising Kurds throughout the region with 3,000 fighters from the Kurdistan Workers’ Party (PKK) based in Iraq’s Qandil mountains reported to be crossing from Iraq into Syria and heading for Kobani.

The Turkish security forces closed the border for a period on Sunday after clashes between them and the refugees. They fired tear gas and water after stopping Kurds taking aid to Kobani according to one account, or because stones were thrown at them as they pushed back crowds of Kurdish onlookers, according to another. Most of those crossing are women, children and the elderly, with men of military age staying behind to fight.

Many Kurds are expressing bitterness towards the Turkish government, claiming that it is colluding with ISIS to destroy the independent enclaves of the Syrian Kurds, who number 2.5 million, along the Turkish border.

Nevertheless, the strange circumstances of both the capture of the 49 Turks and their release shows that Ankara has a different and more intimate relationship with ISIS than other countries. Pro-ISIS Turkish websites say that the Turks were released on the direct orders of “the caliph” Abu Bakr al-Baghdadi. They had been moved to Raqqa, the Syrian headquarters of ISIS from Mosul, and both men and women were well-dressed and appeared to have suffered little harm from their imprisonment. This is in sharp contrast to the treatment of Alan Henning, the British taxi driver seized when taking aid to Syria, and of the journalists who have been ritually murdered by ISIS.

A number of factors do not quite add up: at the time the diplomats and their families were seized in June it was reported that they had asked Ankara if they could leave Mosul, but their request was refused. It was later reported by a pro-government newspaper that the Consul-General in Mosul, Ozturk Yilmaz, had been told by Ankara to leave, but had not done so. Former Turkish diplomats say that disobedience to his government’s instructions by a senior envoy on such a serious matter is inconceivable.

Critics of Erdogan and his Prime Minister Ahmet Davutoglu say that since the first uprising against President Bashar al-Assad in 2011 they have made a series of misjudgements about developments in Syria and how Turkey should respond to them.

Having failed to persuade Bashar al-Assad to make changes, they assumed he would be overthrown by the rebels. They made little effort to distinguish jihadi rebels crossing the 560 mile long Syrian-Turkish border from the others. Some 12,000 foreign jihadis, many destined to become suicide bombers, entered Syria and Iraq from Turkey. Only at the end of 2013, under pressure from the US, did Turkey begin to increase border security making it more difficult for foreign or Turkish jihadis to pass through, though it is still possible. A Kurdish news agency reports that three ISIS members, two from Belgium and one from France, were detained by the Syrian Kurdish militia at the weekend as they crossed into Syria from Turkey.

The hostages had no idea they were going to be freed until they got a telephone call from Davutoglu. While treated better than other hostages, they were still put under pressure, being forced to watch videos of other captives being beheaded “to break their morale” according to Yilmaz. He said that ISIS did not torture people though it threatened to do so: “The only thing they do is to kill them.”

“The Turkish government may not be collaborating with ISIS at this moment, but ISIS has benefited from Turkey’s tolerant attitude towards the jihadi movements. As with other anti-Assad governments, Ankara has claimed that there is a difference between the “moderate” rebels of the Free Syrian Army and the al-Qaeda-type movements that does not really exist on the ground inside Syria,” the article said.