Victims of terror attacks are a symbol of the constant need to guard freedom and the rule of law against threats, King Felipe VI of Spain has said at a ceremony marking the 20th anniversary of one of Europe’s deadliest extremist attacks.

“Remembering, just like justice and truth, is a commitment that cities make to terror victims, to restore and protect their dignity,” Felipe told officials attending the European Remembrance Day for Victims of Terrorism.

The annual event was held this year in Madrid.

March 11 was chosen as a day of continent-wide commemoration of terrorism victims after the commuter train bombings in the Spanish capital, which were carried out by Islamic extremists on March 11 2004 and killed 193 people.

Spanish Prime Minister Pedro Sanchez, senior European officials, and survivors and family members of victims from several European countries were present.

“You paid the price for the hate aimed at our values, our societies, our democracies,” European home affairs commissioner Ylva Johansson told the survivors. “You are not alone.”

Mr Sanchez compared memories of the Madrid attacks with others in New York, London and Paris.

“Whoever witnessed that extreme demonstration of violence (in Madrid) can never forget it,” he said.