A man has been arrested on suspicion of terrorism offences in connection with the Manchester Arena bombing.
A 24-year-old was arrested at Manchester Airport, police said.
He was been detained on suspicion of engaging in the preparation of acts of terrorism/assisting others in acts of preparation under section 5 of the Terrorism Act (2006).
The man, who is from the Fallowfield area of Manchester, was arrested shortly after arriving back in the UK, the force added.
He remains in custody for questioning.
GMP said the arrest is in relation to the terror attack at Manchester Arena on the night of May 22, 2017.
In the attack, 22 people were killed.
The senior investigating officer for the investigation, Simon Barraclough, said: "Greater Manchester Police remains firmly committed to establishing the truth surrounding the circumstances of the terror attack at the Manchester Arena.
"Whether that is by supporting the on-going public inquiry or by continuing to pursue leads with regards to the criminal investigation.
"Over four years have passed since the atrocity took place but we are unwavering in our dedication to follow each line of enquiry available so that we can provide all those affected by the events at the arena with the answers they rightly deserve."
