More than 2,000 Lao people are arriving in Nong Khai province every day after the Thai-Laos border checkpoint reopened.
Some Thais have smuggled petrol into Laos to profiteer from fuel sales there, said Nongkhai Customs House.
Pakin Tiabkam, head of customs control at Nong Khai Customs House, said 2,000 people are crossing the border checkpoint a day, up from 300 people per day before travel restrictions were lifted.
He said 30,000 foreigners crossed the Nong Khai border checkpoint during May 9-31 and 28,000 Thais travelled to Laos. Also, 5,500 cars with foreign licence plates entered the kingdom and 1,700 cars from Thailand travelled to the neighbouring country.
Reporters said a large number of cars from Laos had visited petrol stations in Nong Khai to fill their tanks before heading back to Vientiane, the capital of Laos. The current retail price in Laos is approximately 10 baht higher than in Thailand.
With the currency exchange rate of 450 Lao kips per one baht, the retail price of benzine 95 octane in Laos is 52.82 baht per litre. Benzine is quoted as 41.26 baht per litre and diesel at 40.35 baht per litre.
In Thailand, the benzine 95 octane retail price is 51.91 baht per litre. Benzine is 44.50 baht per litre and diesel is 32.59 baht per litre.
With just 25 kilometres separating Vientiane and Nong Khai, many Lao drive to Thailand for business and travel. Many also leave Nong Khai with a full tank as petrol prices in Laos are high and demand is rising.