By Aung Hla Tun
YANGON (Reuters) - Aftershocks rattled central Myanmar after an earthquake that killed at least 11 people, with that toll likely to rise on Monday as several workers were missing after a half-built bridge collapsed on the Irrawaddy River.
The magnitude 6.8 earthquake early on Sunday struck about 60 km (37 miles) northwest of Mandalay, Myanmar's second-biggest city, near the town of Shwebo. It was felt in Thailand and other neighboring countries.
Several large aftershocks were felt during the day and state television said one of 5.7 magnitude hit just after midnight.
"We can confirm that a total of 11 are dead, while over 50 are injured and four are missing," a senior official at the Ministry of Relief and Resettlement told Reuters, asking not to be identified as he was not authorized to speak to the media.
Damage from the shallow initial earthquake was not as serious as first feared, but small towns near the epicenter suffered.
In Thabeikkyin, a town of 4,200 people on the east bank of the Irrawaddy north of Mandalay, three people died and 35 were injured, according to official media, which said Vice-President Sai Mauk Kham visited the town on Sunday.
About 100 houses, four schools and 21 Buddhist religious buildings were reported damaged there.
A police officer in Shwebo said on Sunday that two people had died and 20 had been injured in nearby Kyauk Myaung. The Radana Thinga Bridge being built over the river in the area had collapsed and five workers were missing, he said.
State television, the usual mouthpiece for government statements in Myanmar along with state-run newspapers, had said late on Sunday that 15 workers at the site were unaccounted for.
The region north of Mandalay has several gold and mineral mines and on Sunday at least 10 people were reported to be trapped in one of the gold mines. However, police and other authorities in the area were unable to confirm that on Monday.
Myanmar is among Asia's poorest countries.
A quasi-civilian government has opened up the country since taking over in March 2011 from the military, which had ruled for nearly 50 years.
The military regime was condemned by humanitarian agencies in 2008 for initially refusing international help to cope with Cyclone Nargis, which killed more than 130,000 people.
President Barack Obama is set to become the first U.S. leader to visit Myanmar this month, the strongest international endorsement of the country's fragile democratic transition.
Obama will travel to Myanmar during a November 17-20 tour of Southeast Asia that will also take in Thailand and Cambodia. It will be his first international trip since winning a second term last week.
(Writing by Alan Raybould; Editing by Robert Birsel)