Nine people were wounded early Sunday as three near-simultaneous explosions rocked Manila and the city of Lipa on the eve of Philippine independence day, police said.

Members of the Philippine police force inspect damages caused by a bomb on a bus used as a mobile police outpost in northern Manila. Four people were injured as three near-simultaneous explosions rocked Manila and the city of Lipa on the eve of Philippines independence day.[AFP]

All of the injured were hit by shrapnel as a bomb tore through an outdoor chicken market in Lipa, 75 kilometers (47 miles) south of Manila, police said.

At about the same time a second bomb exploded at a police outpost in northern Manila and a third explosion was reported at a central Manila park near to a police station.

No group has yet claimed responsibility and police would not say if they thought the attacks were related.

Manila police chief Vidal Querol said his men were on full alert and security would be redoubled for Monday's activities, in which President Gloria Arroyo is expected to take part in a parade at a park near Manila Bay.

"Let us not cower in fear because these people who have planted these explosives hope that they would be able to turn away people and ruin our economy," he said in a television interview.

"There was an explosion. Then I saw two men running way," Lipa fruit seller Eduardo Cardona told AFP. "One was telling the other, 'There, it has gone off.'"

Cardona said he later saw one man on the ground crying for help. ABS-CBN network said it counted nine wounded in two area hospitals.

The blast caused little other physical damage. Explosives experts were seen looking for evidence on the city's main avenue.

The northern Manila blast tore through an old bus that was being used as a temporary police station.

Police officer Reyme Custodio, one of two officers on duty at the time said he had just stepped off the vehicle to buy coffee when he heard an explosion.

The central Manila blast damaged some ornamental plants and left a small crater in the ground.

The attacks followed another blast on Friday outside the home of Dennis Pineda, mayor of the northern town of Lubao and a political ally of President Arroyo. The politician was unhurt.

On June 1, Armand Sanchez, the governor of Batangas province which includes Lipa, was seriously wounded in a bomb attack on his car that killed two of his aides.

Police have been on heightened alert ahead of the June 12 anniversary of the 1898 Philippine revolt against the colonial government of Spain, which Manila celebrates as its independence day.

The islands were subsequently ceded to the United States after the end of the Spanish-American war and the Philippines finally won its independence 48 years later when the US ended colonial rule after World War II.