Armed men in the Philippine capital Manila have kidnapped the son and daughter of a congressman as they were being taken to school.

A senior police officer, Rodrigo de Gracia, said the children, aged five and 10, were snatched when the van in which they were travelling came under fire.

Arroyo has ordered a crackdown on the problem

Their father, Julio Ledesma, a wealthy member of parliament for the central province of Negros Occidental, was not in the van at the time.

No reason was given for the kidnapping, but kidnapping for ransom has become common in the Philippines in recent years.

President Gloria Arroyo has ordered a campaign against kidnap gangs, saying they scare investors and damage the country's reputation.

Gunfire

Four men firing assault rifles were involved in the snatching of Carlos Tomas, aged five, and Cristina, 10, police investigators said.

Police said the attackers used two vehicles to block the family's vehicle and the tyres were shot out to prevent them driving off.

The gunmen also fired at surrounding houses to deter anyone from coming to the children's aide, police said.

The family's driver was injured while trying to fight off the gunmen, who smashed the windows of the vehicle with their rifles.

The children's nanny was not hurt in the incident.

Kidnap for ransom

Mr Ledesma, a widower, comes from a wealthy sugar-producing family.

He is regarded as a low-key politician, but he has been in the news recently for his engagement to a famous young Filipina actress, Assunta de Rossi.

Kidnapping has become a particular problem in the south of the Philippines in recent years, where guerrilla groups are active.

In Manila it has tended to be the work of criminal gangs kidnapping rich businessmen or their family members for ransom.

But experts say this new incident marks a departure from previous abductions as until now the families of politicians have been spared.