A plastic explosive, “much more powerful” than that used in previous car bombs, is believed to have caused the blast that killed journalist Daphne Caruana Galizia on Monday.
Police sources said the sheer force of the explosion and an account by an eyewitness of what happened when the bomb went off pointed to the use of Semtex, a demolition compound often used by terrorist organisations in large-scale attacks.
The sources added that if it had indeed been Semtex, it would be a first in Malta.
It is not clear if the bomb was in the car or on the road.
Frans Sant, who lives down the road from Caruana Galizia, has described the moment her car exploded saying there was a small explosion (possibly a detonator) followed by a more powerful explosion (the main charge).
Dutch forensic experts arrived yesterday to assist in their investigation. The FBI have also been called in.