By Lamine Ghanmi

CASABLANCA, Morocco (Reuters) - Morocco pledged to wage war against terrorism "without respite" on Monday after a suspected suicide bomber was blown up in a Casablanca Internet cafe during a tussle with the owner of the premises.

Police were questioning a man who was found to be carrying explosives as he tried to flee the scene in Sidi Moumen, a slum district of the north African kingdom's commercial capital.

"This is an incentive to pursue the war on terrorism without respite," Communication Minister Nabil Benabdallah told Reuters, adding the incident was "in the framework of horrendous terrorist acts in Morocco and other Maghreb countries".

Governments in North Africa fear violence may spill over from Algeria after the Salafist Group for Preaching and Combat renamed itself Al Qaeda Organisation in the Islamic Maghreb with the aim of fusing similar Islamist groups together.

Security officials said on Sunday night a man with explosives hidden under his clothes had a dispute with the cafe proprietor and the blast occurred as the two men came to blows.

The man armed with explosives was killed and four people were wounded in the blast. The official MAP news agency named the dead man as Abdelfattah Raydi, an unemployed 23-year-old who was sentenced to five years imprisonment in 2003 under anti-terrorism legislation.

He was granted a royal pardon in 2005, the agency said without elaborating.

Another man at the scene who tried to run away was arrested and also found to have explosives, security sources said. The man, one of the four wounded, was under interrogation.

The blast revived memories in the normally peaceful kingdom of a 2003 attack in Morocco's commercial capital that killed 32 people and the 13 suicide bombers who carried it out.

"It was preparation for an attack," said Mohamed Dariff, Professor of Political Science at University Hassan II in Mohamadia, a specialist in Islamist insurgent groups.

"We see that the strategy of Islamic groups in Morocco hasn't changed -- it's the same as it was in May 2003, of men setting off explosives."

DEAFENING BLAST

Witnesses in the neighbourhood of drab low-rise apartment blocks said they had seen two men enter the cafe, then a short while later a deafening blast echoed through the streets.

Hassan, 45, an unemployed textile worker, told Reuters: "There were about 20 of us sitting in a cafe nearby. Some of us rushed to the Internet cafe and found it completely destroyed."

Investigators said they were trying to determine if the explosion was a suicide attack or if the device detonated accidentally and the man had been planning an attack elsewhere.

Casablanca's Sidi Moumen slum was home to the bombers who carried out the 2003 attack. Sunday was the third anniversary of train bombings in Madrid that killed 191 people.

Morocco, on high alert after a string of bomb attacks last month in neighbouring Algeria, has said it had information about an al Qaeda plot to mount an attack but that the circumstances of the Internet cafe blast were unclear.

"We do not know whether the explosion was a suicide bombing or the explosive device went off inadvertently during the dispute," said an official who asked not to be identified.

"The man used to come to view jihadist Web sites and the dispute was prompted by the Internet cafe owner's decision to prevent him this time from viewing such propaganda material."

There was no immediate claim of responsibility. Last week, security sources said police had arrested the head of the military wing of the Moroccan Islamic Combatant Group.

Police suspect Saad Houssaini, 38, of involvement in the 2003 Casablanca bombings and the 2004 Madrid bombings.

Morocco, a constitutional monarchy heavily dependent on agriculture, has backed the U.S.-led war against terrorism launched after the September 11, 2001, attacks on the United States.

(Additional reporting by Tom Pfeiffer and Zakia Abdennebi)