MANILA - The massacre of at least 22 people in the southern Philippines has exposed a brutal culture of guns, greed and money that has poisoned the nation's political system for decades, experts said Tuesday.

The murders in the southern province of Maguindanao on Monday are feared to be only the first of many killings ahead of next year's national elections, when posts from village chiefs to the president will be up for grabs.

"This explosion of violence arises whenever there is an election," said Samira Gutoc, one of the convenors of the Young Moro Professionals, a group helping the government in peace talks with armed Muslim groups in the south.

Indeed, dozens of people are killed each election season in this Southeast Asian nation.

Local political warlords have for generations competed for political power and the accompanying business riches that government posts offer.

These clans are well known to control private armies, who carry out assassinations and counter-attacks against rivals.

The proliferation of over 1.1 million unlicensed firearms, most of them in the hands of rebel groups or paramilitaries, contribute to the general lawlessness in many remote areas, according to police.

In one high-profile murder in the run-up to congressional elections in 2007, a member of parliament from a northern province was gunned down by an assassin hired by his rival on the steps of a Manila church while attending a wedding.

All in all, 121 people were killed in that polling season, according to national police statistics, slightly lower than the 148 who died in the 2004 national elections.

But while the problem plagues the entire country, experts say Maguindanao and other parts of the far southern island of Mindanao -- where a Muslim insurgency has waged for decades -- are particularly volatile.

"Politics in Mindanao is about ownership of power. Public office is perceived as a personal, clannish thing -- a birth right, and they would spill blood for it," Gutoc said.