Nine radical Islamists jailed for their links to the 2003 Casablanca suicide bombings that killed 45 people broke out of a Moroccan top security jail on Monday, the Justice Ministry said.
The nine men escaped from Kenitra prison, 40 km (25 miles) east of Rabat, the ministry said.
"All the measures have been taken to arrest the escaped detainees," it added in a statement, saying authorities were investigating how the prisoners broke free.
A security source said the prisoners escaped through a tunnel they dug out under their cells.
"They literally saw the light at the end of the tunnel in the early hours today," the source said.
The escaped prisoners left a five-line letter, saying their breakout was the only solution to what they called injustice.
Islamist prisoner rights advocacy group Ennassir said the jailbreak coincided with the beginning of a one-day hunger strike by about 1,000 Islamist prisoners held at several prisons across Morocco, including Kenitra's.
"Most of the escaped prisoners had been sentenced to life imprisonment late in 2003 for their links with 2003's Casablanca bombings. It is the first such jailbreak," Ennassir chairman Abderrahim Mohtad said.
Mohtad said the Islamist prisoners were fasting on Monday to protest against what they called mistreatment and repression by prison officials. Authorities were not immediately available to comment on the prisoner allegations.