Vientiane: King Maha Vajiralongkorn and Queen Suthida of Thailand will pay a state visit to the Lao PDR from March 16-18 at the invitation of President Thongloun Sisoulith, the Ministry of Foreign Affairs announced today. The visit marks their first official trip to Laos as reigning monarch and queen.According to Lao News Agency, the visit is expected to further strengthen the long-standing friendship and cooperation between Laos and Thailand as the two neighbours commemorate the 75th anniversary of diplomatic relations.