About 500 anti-election protesters surrounded the provincial sports stadium, the venue for constituency MP registration in the southern province.
A total of 300 police were employed inside and around the stadium to ensure peace and order.
At 9pm Sen Rakrong, head of the provincial election committee, declared that registration had been cancelled over fears for the safety of EC officials and their equipment, as the number of protesters was increasing.
The first and second days of registration had been postponed due to pressure from the protesters and four election committee members resigned as a result.
The new four members had just been elected, but were unable to perform their duty on the third day of registration.