The man, 20, was detained at a house in the Welsh capital Cardiff by counter-terrorism officers, London police said.
He is the seventh man to have been arrested over the attack at Parsons Green station in London on Sept. 15 which injured 30 people.
Last Friday, teenager Ahmed Hassan appeared in court charged with attempted murder over the attack. He was remanded in custody until Oct. 13.
(This story has not been edited by NDTV staff and is auto-generated from a syndicated feed.)
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