Guerrilla fighters from Myanmar’s Karen ethnic minority claimed Monday to be close to seizing control of a major trading town bordering Thailand, as soldiers and civil servants loyal to the military government appeared to be preparing to abandon their positions. The occupation of Myawaddy town by the Karen National Liberation Army, the armed wing of the Karen National Union, or KNU, appeared imminent as the guerrillas seized or besieged strategic army outposts on the town’s outskirts, a spokesperson and members of the KNU said Monday. Myawaddy, in Kayin state, is Myanmar’s most active trading post with Thailand, and its fall would be the latest in a series of shock defeats suffered by the army since last October, when an alliance of three other ethnic rebel groups launched an offensive in the country’s northeast.