SEOUL — South Korea has received assurances from Myanmar that it will no longer buy weapons from North Korea, an aide to President Lee Myung-bak said Tuesday.

President Thein Sein of Myanmar acknowledged that his country had bought conventional weapons from North Korea over the past 20 years but vowed in a meeting with Mr. Lee in the Burmese capital on Monday to end that practice, said the aide to the South Korean president, Kim Tae-hyo.

The presidential office in Seoul confirmed Mr. Kim’s comments.

Mr. Thein Sein also indicated Tuesday that Myanmar had not pursued the development of nuclear weapons and vowed to honor a U.N. Security Council resolution that bans countries from engaging in activities that could assist North Korea’s nuclear and long-range missile programs, Mr. Kim said.

“I urged President Thein Sein not to do any trade with North Korea that violates international regulations,” Mr. Lee said at a joint news conference with the Burmese opposition leader Daw Aung San Suu Kyi in Yangon on Tuesday, the South Korean news media reported.