LONDON (AFP) - British police said on Monday they had arrested a 21-year-old man returning from Istanbul to London's Stansted airport on suspicion of being involved in terrorism abroad.
It is the sixth anti-terrorism arrest in the past week involving travel to Turkey, which shares a border with Syria.
London's Metropolitan Police declined to say whether the latest arrest was linked to the conflict in Syria, where numerous Britons have travelled to fight with jihadi groups.
"It wasn't for any threat to the UK," a police spokesman told AFP.
The 21-year-old was stopped at Stansted at 8.40pm (4.40am Singapore time) on Sunday after flying in from Istanbul via the German city of Stuttgart, police said in a statement.
Shortly after 1.00am (9am Singapore time) on Monday, he was formally arrested on suspicion of being involved in the commission, preparation and instigation of terrorism offences.
Detectives have since carried out searches of three addresses in connection with the investigation, according to the statement, and inquiries are ongoing.
In another case this week, two 21-year-old men from Birmingham in central England were charged on Friday with travelling to Syria for the purposes of terrorism.
Mohammed Nahin Ahmed and Yusuf Sawar had been arrested at London's Heathrow Airport on January 13 on a flight back from Istanbul.
They appeared in court on Saturday, where the prosecutor claimed they travelled to Syria in May 2013 using one-way tickets to Turkey.
Sawar's mother found a note explaining the reason for her son's trip was to engage in 'jihad', prompting her to call the police, according to a police statement.
Sawar also said he had aspirations to join a group alleged to be linked to Al-Nusra Front, which is affiliated with Al-Qaeda, and left instructions to cancel his mobile phone contract and settle his debts, police said.
In an another unrelated case, another Birmingham man, also 21, was arrested on Friday on suspicion of attending a terrorist training camp in Syria. He was detained after flying back from Istanbul to London's Gatwick airport.
On Thursday, two women aged 26 and 27 were also arrested on suspicion of terror offences, including one who was about to catch a flight to Istanbul.
Police would not comment on whether the arrests were linked to Syria.
Foreign Secretary William Hague said last week that "hundreds" of Britons were believed to have gone to fight in Syria and security forces were doing their best to monitor the situation.
A jihadi defector told the Daily Telegraph newspaper in an interview published on Monday that Al-Qaeda is training hundreds of Britons fighting in Syria to become jihadists, and urging them to carry out attacks when they return home.
Several other European countries have had similar problems with French President Francois Hollande saying last week that 700 people had left France to join the fighting in Syria.