Spanish police have arrested 16 people suspected of having links to Islamic terror groups. Five of the suspects were held for alleged involvement in the Madrid train bombings of March 2004. The other 11 men are thought to have links to Abu Musab al-Zarqawi, the Jordanian militant spearheading the insurgency in Iraq. Some 500 police took part in raids in Madrid and a number of regions across Spain, the interior ministry said. No weapons or explosives have been reported found. A series of co-ordinated bombs attacks on trains in Madrid on 11 March last year killed 191 people and sparked a wave of police raids on suspected militants. Dozens have been arrested and several have already faced trial. Twenty-four men charged with terror offences recently appeared in court, three of them accused of involvement in planning the 11 September 2001 attacks on the US. As well as Madrid, Wednesday's arrests were made in the north-eastern region of Catalonia, Andalucia in southern Spain, Levante in the east, and Ceuta, Spanish territory on the northern Moroccan coast.