The Foreign Office is seeking clarification from the Turkish authorities over reports that Ankara swapped European jihadis, including two Britons, in return for its diplomats held hostage by Islamic State (Isis).

British officials said that while there is some ambiguity over the exact circumstances, they are not ruling out that the Turkish government, a member of Nato, made the deal.

The British government takes a hard line against deals with terrorists in return for hostages as does the US. But other governments in Europe and elsewhere do make trades, often without acknowledging them publicly.

Details of the reported trade, published in the Turkish daily Taraf, surfaced in the wake of the beheading of Alan Henning, the British taxi driver, by Isis.

Isis captured 49 Turkish consulate staff in Mosul, the second biggest city in Iraq, in June. The 46 Turks and three Iraqi nationals were held for 101 days until 20 September. Turkey has claimed that the release was achieved purely through diplomacy.

Taraf reported that 180 Isis members wounded in US airstrikes in August and being treated in Turkish hospitals under US orders not to release them were swapped for the 49 hostages with local Arab Sunni tribal leaders acting as mediators.

Taraf alleged that 180 Isis militants were rounded up from Turkish hospitals and prisons and taken to a military outpost in Van province.

British counter-terrorism officers are concerned about two Britons reported to have been returned to IS as part of the trade, Shabazz Suleman, aged 18, and Hisham Folkard, 26.

A Foreign Office spokesman, referring to Suleman, a school student from High Wycombe, said: “We are aware that a British national was reported missing in Turkey. We continue to provide consular assistance to the individual’s family. We are in contact with Turkish authorities to clarify the circumstances of this case.” While publicly the British government position is to be critical of other governments for doing deals, a foreign policy analyst suggested that privately the deal this time may be in British and US interests, as the release of its diplomats might free the Turkish government to take a more robust approach to Isis.

The British government says it does not pay ransoms but payment by families is a grey area: families paying a ransom is not illegal but funding terrorism is, and the Foreign Office would advise families to that effect.

• This article was amended on 7 October 2014. An earlier version referred to Istanbul as the capital of Turkey.