A notification issued this week on the airline's official website announced the cancellation of flights to Singapore for the Summer Schedule 2018.
Direct flights between Vientiane's Wattay International Airport and Singapore's Changi International Airport had resumed in late October last year after a suspension earlier in 2017 for unspecified reasons.
"We will announce the resumption of our flight schedules as soon as Lao Airlines is ready for operation upon further notice," said the company's announcement.
A representative of a Vientiane-based travel agency, who asked not to be named, said bookings on Lao Airlines at her company, especially on the Vientiane to Singapore route, were not so good.
"I have no idea about any specific reasons but this may be because of the presence of several international airlines or because the flight schedule does not suit passengers' needs," she said.
Giving an example, she said some customers wanted to fly to Singapore on a Tuesday and come back to Vientiane on Thursday but Lao Airlines only had flights on Wednesdays, Fridays and Sundays.
"This could be the reason that many passengers make reservations with other airlines that are operating in Vientiane," she said.
Currently, Lao Airlines has direct flights to several major cities in Cambodia, China, Thailand, Vietnam and the Republic of Korea.
According to the company's plans, its network extends to 12 international destinations and six locations within Laos while new routes are planned for various ASEAN countries as well as China's Hong Kong and Taiwan, and Japan.
Other airlines providing international flights out of Laos include AirAsia, Bangkok Airways, China Eastern Airlines, Thai Airways, and Vietnam Airlines. In addition, there are some foreign chartered flights to Laos.
At the end of 2016, Singapore's SilkAir launched flights to Vientiane and Luang Prabang. It operates three weekly flights on Mondays, Thursdays and Saturdays. Its flights from Singapore make a stop in Vientiane and then continue to Luang Prabang before heading back directly to Singapore.
SilkAir is also set to offer more flights to Laos under a code-share agreement with Lao Airlines.
According to figures from 2016, two-way trade between Laos and Singapore reached US$30 million, more than doubling from US$13 million (S$17 million) in 2015.
In the same year, more than 6,000 Singaporean tourists visited Laos.
Also in the same year, Singaporean companies invested US$187 million in 79 projects in Laos, making the country the 11th largest foreign investment source.