Nine Islamic extremists jailed for a deadly bombing campaign in Morocco today escaped by tunnelling their way out of high-security prison.

The militants escaped from the Kenitra prison, north of Rabat, after dawn prayers, officials said.

A justice ministry statement said that "all measures have been taken to arrest the escaped detainees", although they still remain at large.

The group had been jailed for their part in planning suicide bombings in Casablanca in 2003, which killed 45 people including a dozen suicide bombers.

Two militants were arrested before they could detonate their explosives. The attacks were the deadliest ever in Morocco, and were suspected to have been carried out by groups affiliated with al-Qa'eda.

A Spanish restaurant, a hotel popular with foreigners and Jewish a cemetery were among the targets.

The jailbreak coincided with a one-day hunger strike by about 1,000 Islamist prisoners across the country, said Ennassir, an Islamist prisoner rights group.

Ennassir chairman, Abderrahim Mohtad, said claimed the fast was in protest against mistreatment and repression by prison officials.

Morocco's prisons are overcrowded and squalid and most of the 60,000 prisoners complain of lack of decent food and access to healthcare, human rights groups said.

Islamist detainees want to be given "political prisoner status" which would allow them better conditions.