The Paris-based Reporters Without Borders called on authorities to hold a full investigation into the murder of popular radio broadcaster and provincial publisher Rowell Endrinal in the central Philippines on Wednesday.

Endrinal was a known critic of the local political elite and his murder, ''if left unpunished... could open the wsay for more attacks on journalists,'' the group said in a statement.

The group called on Interior Secretary Jose Lina to carry out a thorough investigation to ensure that Endrinal's killers were caught and punished.

It noted that seven journalists were murdered in the Philippines last year, one of the highest records since democracy was restored in this country in 1986.

Some of the assassins were arrested but the masterminds of the killings have gone unpunished, Reporters Without Borders commented.

Last year, President Gloria Arroyo offered a million-peso (17,920-dollar) bounty for tips leading to the arrest of suspects of each murdered journalist in the Philippines in the past five years.