BANGKOK — Ignoring criticism that a huge hydroelectric dam could irreparably damage the ecology of the Mekong River, the government of Laos said Tuesday that it was pushing ahead with the multibillion-dollar project, the first dam to be built on the lower portion of the iconic river.

“I would say I’m 100 percent sure it’s going ahead,’’ Daovong Phonekeo, deputy director general of the Laotian Department of Electricity, said by telephone Tuesday.