The aircraft was carrying about 20 people including Defence Minister Douangchay Phichit, the Vientiane governor and other prominent figures, foreign ministry spokesman Sek Wannamethee told AFP quoting information from the Thai embassy in Vientiane.
There was no immediate confirmation from Laos's secretive communist government.
In October last year a civilian airplane operated by Lao Airlines plunged into the Mekong River in bad weather killing all 49 people on board.