The arrest was made on Thursday at Heathrow Airport (Picture: PA).
A man has been arrested on suspicion of terror offences after arriving at Heathrow Airport from Turkey.
The unnamed 26-year-old was met by the Metropolitan Police's counter-terrorism command.
Earlier the Turkish Ministry of Foreign Affairs confirmed a Briton was one of several IS suspects deported this week.
The Home Office refused to confirm the identity of that suspect, although reports suggest the man arrested was British.
He remains in custody, although the Home Office said it used various tools to manage the threat of any Briton returning to the UK from Syria, including Terrorism Prevention and Investigation Measures (TPIMs) notices placing restrictions on that person.
It comes amid a recent push from Turkey to repatriate supporters of the so-called Islamic State group (IS) who were held in Syria.
Nine others are currently awaiting deportation to Germany.
Turkey has increased its efforts to return prisoners to their home countries after the West refused to support its cross-border offensive into northern Syria last month.
Following recent EU sanctions over gas drilling off Cyprus, Turkish leader Recep Tayyip Erdogan has threatened the continued release of suspected terror suspects.
Turkey says it is holding nearly 1,200 foreign suspected IS members, and continues to criticise Western governments for their reluctance to take them back.