The robbers, possibly working with insiders, had attacked the Rizal Commercial Banking Corp branch in Cabuyao, south of Manila, and fled before its usual opening time of 9am.

It was not immediately known how much, if any, money was stolen.

Bank clients alerted police after the bank failed to open at 9am. Police found nine bodies sprawled on the floor inside the bank, and the bank manager still alive, with a gunshot wound to the head.

'This is the handiwork of the devil and we will not let this pass,' Chief Superintendent Ricardo Padilla said. 'They were killed in a gangland-style execution - each of the victims shot in the head while lined up.'

Chief Superintendent Padilla said the robbers could have used silencers because residents in the area heard no gunshots coming from the bank.

Laguna provincial police chief Felipe Rojas said that one security guard who was supposed to come in for daytime duty was missing, leading the authorities to suspect he was involved in the robbery. The night-duty guard was among the dead.

Among those killed was a depositor who apparently arrived early. The police chief said there was no sign of forceful entry, but the bank's backdoor was open.

'They (robbers) were probably here early morning,' he said. 'There was no reason why they should kill the employees, so most probably they knew one or two of the robbers.'

He added that the bodies showed no bruises or other signs of resistance.

Bank vice-president Edwin Ermita said the assailants had tried to hide the body of the security guard under a tarpaulin at the rear of the bank.

Police later recovered an abandoned vehicle nearby which they believe the suspects used to escape.

The vehicle was owned by one of the bank employees and would be checked for fingerprints, said the police chief.

He said the victims, including two inside the open bank vault, were shot point-blank.

The number of robbers was not immediately clear, but he said 'many' took part 'because this was a very complex operation'.

Police recovered empty bullet shells from at least four different types of guns.

Philippine and US currency worth a combined US$10,000 (S$14,000) was found strewn on the floor of the bank, but the amount taken by the robbers was not immediately known.

'Definitely, (they) took more' than what they left behind, said the police chief.

The bank's operations manager was still fighting for his life in a nearby hospital.

Bank robberies are common in this country but rarely as bloody. The police chief said this was the worst robbery in the country's history.

ASSOCIATED PRESS, AGENCE FRANCE-PRESSE