Thailand put its U.S.-trained army on alert, reinforced armed mobile patrols along the shallow, narrow Moei River separating the two countries, and evacuated Thai villagers from the area of western Thailand near Mae Sot town.

Burma's election on Sunday was an attempt by the ruling military junta to convince the U.S., European Union and other critics that the Southeast Asian nation is evolving toward democracy.

The heavily manipulated polls, however, resulted in international condemnation by President Obama and other leaders, who predicted that Burma would continue to be run by a dictatorship heading a parliament in which 25 percent of the seats were assigned to the military's candidates.

The junta was expected to announce its anticipated landslide election victory later this week for the 1,159 seats up for grabs — mostly contested by the military's other candidates — in the bicameral parliament and 14 regional assemblies.

Parts of northern and eastern Burma's mountainous regions were not included in the election after the regime considered those zones too violent because ethnic rebels of various tribes — including Karen, Karenni, Shan, Kachin, Wa and others — have been fighting for autonomy on and off since Burma became independent from Britain in 1948.

Sunday's sudden conflict continued through Monday, after a frustrated faction of the Democratic Karen Buddhist Army (DKBA) guerrillas briefly seized a police station and post office in the eastern Burmese town of Myawaddy, across the river from Mae Sot.

For several years, the DKBA has been tightly allied with Burma's military regime as a collaborating Karen force being used to attack the Karen National Union (KNU), made up mostly of Christian rebels in the mountainous jungle zone where the tribal group has long dreamed of autonomy or independence.

"DKBA Battalion 902, under Brigade 5, led by Lt. Col. Saw Kyaw Thet, was involved in the clashes and had fired heavy weapons near the Thai-Burmese Friendship Bridge," reported Mizzima News, staffed by pro-democracy Burmese activists and other reporters in Burma and the region.

"I had to take cover. The rebel forces are in front of this shop. They fired about 10 [rocket-propelled grenade] shells toward the Myawaddy bridge," a shopkeeper in Myawaddy told Mizzima News.

Burma's troops rushed to the town and regained control, pushing the DKBA faction to the outskirts. The skirmishes in and near Myawaddy wounded least 10 people, Associated Press said Monday.

Farther south along the border, at the Three Pagodas Pass crossing point, fighting reportedly erupted inside Burma for about an hour.

Burma's military had arranged cease-fire agreements with several ethnic rebel groups during the past few years but recently demanded that those guerrillas be absorbed into a border patrol force under the command of Burma's army.

The DKBA faction apparently refused, turned traitor against the regime and unleashed the assaults, perhaps hoping its enemies, the KNU, might support it. If those Karen fighters do not, the DKBA faction may have to suffer banishment in the jungle, hunted to the death by Burma's fearsome, experienced troops.

Rivalries have weakened the Karen during the past several years while they tried to survive Burmese military assaults, malaria, hunger and a bleak nomadic existence in the rugged jungle.