London, April 15 (IANS): Four British citizens were arrested on Wednesday at the airport in Manchester for allegedly being involved in terrorist activities, Efe news agency reported citing police that also investigate nationals travelling to Syria.

The suspects, aged between 22 and 47 years old and whose identities have not been revealed, come from the northern town of Rochdale, police officials said, while they did not specify whether those arrested were returning from Turkey with the intention of illegally crossing into Syria.

On Tuesday, according to police, officers arrested two others at the airport in Birmingham, including a 31-year-old man and Waheed Ahmed, the 21-year-old son of Manchester district Labour councillor Shakil Ahmed, after Turkish authorities sent him home on suspicion of terrorist activities in Syria.

The six are being questioned by the police, who are working with the cooperation of the City of Rochdale and religious leaders as part of the investigation.

The authorities have expressed concern about cases of young people travelling to Turkey to then cross into Syria to join the Islamic State (IS) terrorist group.

In February, three British teenaged girls from an east London neighbourhood travelled to Istanbul, and made their way to Syria to supposedly join the IS, authorities recalled.