World Bulletin/News Desk

Renewed fighting between government troops and rebels has added to widespread fears that hostilities along Myanmar’s troubled borderlands could derail the country’s ambitious peace process.

A 12-year-old boy was among four civilians killed by artillery fire near Myanmar’s border with Thailand in eastern Karen state Saturday when a shell landed near a major road, according to local media.

Nine others were injured in the incident on the Myawaddy-Kawkareik road, a major trading route between Thailand and Myanmar.

Anti-government rebels who have been locked in skirmishes with Myanmar’s army in recent weeks have denied responsibility for the attack, the Democratic Voice of Burma (DVB) reported Monday.

A spokesman for the rebel Democratic Karen Benevolent Army (DKBA) told local media that his group’s positions were "too far" from the scene to have launched the attack.

“There are many other ethnic armed groups active in the area,” he told DVB. It is believed the attackers were targeting a government position near the site of the explosion.

President Thein Sein, the head of a quasi-civilian government that took power in 2011 after decades of military rule, has vowed to negotiate a nationwide ceasefire with more than a dozen ethnic groups as part of a series of sweeping reforms.

Of Myanmar’s 16 major rebel groups, 14 have signed cease-fires, but the deadline for a nationwide deal has been repeatedly pushed back amid stalemate at the negotiating table and sporadic fighting in rebel territories.

Negotiators left empty handed after the latest round of talks last month.

Thein Sein recently hinted that a historic general election scheduled for next year could be postponed if his government doesn’t achieve peace beforehand.

The Buddhist DKBA was formed after breaking away from the larger Karen National Union, a predominantly Christian rebel group, in 1994.

The splinter group has since fought alongside government troops against the Karen National Union, and signed a short-lived cease-fire deal with the government in 2011.

Fighting with various ethnic insurgencies has raged for decades in Myanmar.