Myanmar’s opposition party headed by Aung San Suu Kyi on Wednesday condemned the assassination of a top Karen rebel leader, who was a critical link between the insurgents and the pro-democracy movement.

The National League for Democracy “regretted the assassination and strongly condemned any armed terrorist resolution” of political problems, the party said in a statement, referring to the slaying of Pado Mahn Sha in a Thai border town on February 14.

“Political problems have to be solved politically,” the statement said. The party stopped short of laying blame on anyone for his death.

Pado Manh Sha, who ranked third in Myanmar’s largest rebel group the Karen National Union, was shot dead by two gunmen at his home in the Thai-Myanmar border town of Mae Sot.

Myanmar has been hit by a series of small bomb blasts and rebel shootings since December, prompting the ruling junta to blame the Karen National Union (KNU) for the attacks.

The KNU suspects that hired hitmen conducted the killing, possibly on behalf of a pro-junta Karen splinter group.

Myanmar, under military rule since 1962, has signed ceasefires with 17 other ethnic armed groups, but the KNU is one of the few remaining ethnic insurgent groups yet to sign a peace deal with the junta.