Human rights groups have expressed their "shock and outrage" over the arrest of former Guantanamo Bay detainee Moazzam Begg on suspicion of terrorism offences.

Begg, 45, was one of four people detained by West Midlands Counter Terrorism Police accused of alleged Syria-related terrorism activities.

The 45-year-old from Hall Green, Birmingham, spent nearly two years incarcerated at the US detention camp in Cuba before being released without charge. He is accused of attending a terrorist training camp and facilitating terrorism overseas.

A 36-year-old man from Shirely and a woman, 44, along with her 20-year-old son, were also arrested on suspicion of facilitating terrorism overseas.

Human rights groups have condemned his arrest as an act of "harassment against Muslim individuals" who aim to provide humanitarian aid to the victims of the Syrian conflict.

Begg has been open about his travels to Syria. His passport was confiscated by the Home Office in December 2013 after they ruled it was "not in the public interest" for him to travel to the country. He said he was in Syria to investigate claims regarding British and American complicity in torture in the country.

Members of the group Cage, of which Begg became a director following his release from Guantanamo, have claimed his arrest is to ensure any travel to Syria "is deemed suspicious".

Asim Qureshi, research director of Cage, said: "Cage calls on all defenders of civil liberties and the rule of law to stand up and protest against the serious curtailment of yet another victim. The message may be unpalatable to those who wish to shroud their abuse in secrecy but that can never justify an attack on the messengers."

"We are disgusted that Moazzam Begg is being retraumatised with the same guilt by association accusations that resulted in his unlawful incarceration in Guantanamo Bay. We fully support our colleague and see his arrest as politically motivated and as part of a campaign to criminalise legitimate activism."

Massoud Shadjareh, chair of the Islamic Human Rights Commission, said: "As someone who knows Moazzam on a personal level and as a fellow campaigner and activist I am shocked by his arrest. He is far from an extremist and takfiri. As a matter of fact he has always been a vocal critic of sectarian and takfiri elements."

The term Takfiri is used to describe Muslims who accuses another Muslim of apostasy if they do not follow Islamic law in its strictest sense.

Following the suspect's arrest, head of investigations for West Midlands Counter Terrorism Unit, Det. Supt. Shaun Edwards said: "All four arrests are connected. They were pre-planned and intelligence-led. There was no immediate risk to public safety.

"We continue to urge anyone planning to travel to Syria to read the advice issued by the Foreign Office."