Moroccan police have arrested an alleged member of a terror group linked to the Madrid train bombings and suicide blasts in Casablanca in 2003.
Thousands were arrested after the Casablanca suicide attacks
Saad Houssaini was suspected of being a key member of the Moroccan Islamic Combatant Group, police said.
The group, known by its French acronym GICM, has been linked to both attacks.
Mr Houssaini is suspected of being a key figure in the Casablanca attack, but is not a Madrid suspect, Spanish and Moroccan officials said.
He was arrested on Thursday in Casablanca, Interior Ministry spokesman Abderrahman Achour said.
It was unclear exactly what role Mr Houssaini allegedly played in GICM, an al-Qaeda-linked Islamist group which has been banned by countries including the US and the United Kingdom.
Saad Houssaini is suspected of being a key member of GICM
Spanish officials said he was not wanted in connection with the Madrid attacks, and his name had only come up in investigations because of alleged links to the Casablanca attack.
More than 190 people died and 1,500 were injured in the March 2004 Madrid train bombings. Twenty-nine people - including 15 Moroccans - are on trial over the blasts.
Forty-five people - including 12 suicide bombers - were killed in the Casablanca attacks in May 2003.
Thousands of suspects have been arrested in Morocco since the blasts - the first Islamic terror attacks on Moroccan soil.
Moroccan authorities had been hunting Mr Houssaini since 2002 before either of the attacks, Mr Achour said.
GICM is believed to have formed in the late 1990s by Moroccans who had fought or trained in Afghanistan.