"Only the two bombers were killed," a police source told Reuters.

Witnesses said a man blew himself up about six meters (yards) from the American cultural centre.

A minute later, a second blast occurred about 60 meters away from the nearby US consulate.

"His body was blown into four pieces. His head and hands fell into the courtyard of a bank building," said Mohammed Bouhassine, a witness to the consulate blast.

Moroccan security officials said the blasts occurred shortly after the two men approached a policeman manning a checkpoint 100 meters (yards) from the American culture centre.

The bombers set off their explosives after they were denied access to the building, security officials said.

Police also arrested a third bomber after he tried to flee the scene.

"He threw down his explosives belt and ran away," the owner of a coffee shop in the neighborhood told Reuters on condition of anonymity.

"Police chased him and caught him," he added.

A senior police source said the bombers clearly intended to attack the US buildings.

"There is no doubt they aimed at the U.S. targets," said the source. "They made that statement with their own bodies."

On Tuesday, three men blew themselves up in Casablanca as they were pursued by police during its hunt for those behind an explosion that rocked the city in March. A fourth man linked to the group died of injuries he sustained in the police operation.

One man died in the March explosion.

Casablanca was hit by suicide attacks in May 2003, which killed 45 people including 12 bombers.

Mastermind Arrested

Shortly after the failed blasts, Moroccan security services said they arrested the man thought to be the head of the group responsible for deadly explosions in the city this week and a month ago.

The man, along with his deputy, were arrested on Saturday morning in the shantytown of Sidi Moumen, on the outskirts of Casablanca, in the course of police investigations into Tuesday's explosions, reported Agence France-Presse (AFP) reported.

Police said they had discovered where the gang were making their explosives and had also been able to identify the rest of the group and were actively looking for them.

The Moroccan government said today's two bombers were linked to a ring dismantled last month, which included suicide bombers who planned to blow up foreign ships docking at Casablanca's port and hotels in Morocco's main tourist cities.

It insists that the bombers were "home-grown" terrorists who had no links to international terrorism networks.

But analyst Miloud Belkadi begged to differ.

"The bombing today underscores links with Al-Qaeda strategy focusing on US targets. They are different from the suicide bombers killing themselves in slums," he told AFP.

Saturday's attacks followed twin bombings in neighboring Algeria last week, which killed 33 people and wounded 200 others.