In pictures: Madrid car blast

1 of 7 A cloud of smoke rose over the Madrid outskirts after the car bomb blast on Wednesday morning.

2 of 7 A caller to a Basque newspaper warned that militant separatists Eta had planted a device in the capital.

3 of 7 The car exploded outside a convention centre which King Juan Carlos had been due to visit later in the day.

4 of 7 At least 31 people were injured, including five police officers who were near the car when the device exploded.

5 of 7 Most of those hurt were hit by flying glass from nearby buildings.

6 of 7 Firefighters have been working to clear the damage at the blast scene.

7 of 7 Correspondents say Spain has notably increased security since the Madrid bombings on 11 March last year.