COTABATO, Feb 18 (AFP) - Gunmen shot dead a mayoral candidate in a southern Philippine province where 57 people were massacred in election-related violence last year, a policeman said Thursday.

The murder of Errol Sinsuat, a member of President Gloria Arroyo's ruling party, was the second political killing in Cotabato City in a fortnight and occurred despite a state of emergency that was put in place after the massacre.

Motorcycle-riding gunmen shot dead Sinsuat, 38, a district chairman in Blah Sinsuat town, while he was driving his motorcycle through Cotabato City late Wednesday, said city police director Senior Superintendent Willie Dangane.

A policeman who responded to the shooting was also fired upon and wounded, Dangane said.

Sinsuat had been planning to run in the May 10 national elections for mayor of Blah Sinsuat, just outside Cotabato City. His killing was likely related to politics, Dangane said.

Sinsuat's killing took place roughly 20 kilometres (12 miles) from a rural area of Maguindanao province where 57 people were slaughtered on November 23, allegedly by the private army of a powerful local clan, the Ampatuans.

Andal Ampatuan Jnr allegedly led the massacre to prevent a rival from challenging him in the May elections for the post of Maguindanao governor.

Ampatuan Jnr and 197 others, including his father and other members of his family, have been charged with the massacre, which is the worst known case of political violence in this country.

Across the Philippines, which is notorious for its gun culture, elections are plagued by violence with politicians known to use gunmen to eliminate rivals and intimidate voters.

Including the massacre, at least 64 people have been reported to have been murdered in politically related violence in the run-up to the national elections.

Barely two weeks ago, a candidate for the Cotabato City council was gunned down with his two young children wounded in the incident.

More than one million unlicensed firearms are believed to be on the streets of the Philippines, according to police estimates.