MANILA, January 11, 2010 (AFP) - Police shot dead two robbers and arrested 48 other people as they enforced a firearms ban across the Philippines ahead of national elections in May, authorities said Monday.

Police deputy director general Jefferson Soriano said tens of thousands of officers had been deployed to man 3,500 checkpoints set up across the country and enforce the ban on the unauthorised carrying of weapons.

"We want to show to the public that we are dead serious about implementing the nationwide gun ban," Soriano said on the ABS-CBN television network.

The ban is imposed ahead of every Philippine election, but has taken on more significance in recent months following a massacre of 57 people and the separate killings of at least five others in violence linked to the polls.

Soriano said five policemen and three soldiers were among 48 people arrested on Sunday, when the ban began. The policemen and soldiers were carrying weapons while off duty, he said.

National police spokesman Chief Superintendent Leonardo Espina said that police manning a gun-ban checkpoint stopped two armed robbers just outside Manila on Monday, resulting in a gun battle that left the criminals dead.

He said two pistols were recovered from the robbers, who had held up and murdered a corn trader.

The Philippines is well known for its gun culture and violence-plagued political system.

The authorities say there are more than one million unlicensed firearms in the Philippines, and dozens of people are killed each election season when politicians seek to eliminate rivals or critics.

Fuelling the violence are the "private armies" controlled by so-called political warlords.

One such militia allegedly carried out the November 23 massacre of 57 people in the southern province of Maguindanao.

About 100 gunmen controlled by a local mayor, Andal Ampatuan Jnr, allegedly abducted relatives of a rival politician, plus a group of journalists travelling with them to an election office, then murdered them.

The massacre's alleged aim was to stop the rival from running against Ampatuan for provincial governor in the elections.

Since then, at least five candidates in the elections -- at which positions ranging from president to local councillor are up for grabs -- have been shot dead.

Under the terms of the ban, which will last until June 9, civilians with permits to carry guns are also forbidden from taking them out of their homes.

In addition, politicians are not allowed to have armed bodyguards, a common practice normally.

Elections Commissioner Lucenito Tagle said there had already been more than 6,000 requests for exemptions to the ban, mostly from officials who say they need security.

"We are actually trying to discourage it as much as possible. Less guns is what we want," he told reporters.

Those caught illegally carrying weapons can be jailed for up to six years, although not everyone arrested each time the ban is introduced goes to prison.