Public confidence in politics tumbled to the lowest level in 17 months in August, with national unity suffering the worst decline amid a damaging rift between government supporters and detractors, a survey has found.

The Political Confidence Index was at 90.25 in August, down by 2.11 points from the month before - and by 10.91 from the same month last year - according to results of the survey by Suan Dusit Rajabhat University released yesterday.

The index was at its lowest ebb since April last year, when the survey was first conducted.

The previous lowest index of 90.44 was recorded in May, one month after the controversial general election, when the political confrontation between caretaker Prime Minister Thaksin Shinawatra and the anti-government People's Alliance for Democracy was at its height.

The survey involved 6,087 people all over the country between August 20 and last Monday, September 4.

Of the 25 indexes used to measure confidence in Thai politics, "national unity" suffered the worst decline in August, falling 8.46 points from July. It was followed by "national security", down 5.73 from a month earlier.

Only four of the 25 indexes saw an improvement from a month earlier: solving of the drug problem, general performance by political parties, poverty eradication and the price of consumer products.

Of all the indexes, only "news distributed by the media" was above the benchmark of 100 points. It was recorded at 106.03 while the other indexes were below 100.

Three indexes were at their lowest levels in 17 months: national security (78.22), performance by politicians (78.66) and solving corruption problems (84.79).

It was also found that residents of the Northeast had the most confidence in Thai politics (94.46 points) while Bangkok residents had the least confidence (87.13).