The decline of 0.3 per cent was steeper than the falls of 0.1 per cent and 0.2 per cent seen in June and July respectively.
August’s output was just 1.5 per cent higher than in the same month last year.
Manufacturing has failed to recover the ground lost in the recession – output is now 3.6 per cent lower than in 2008.
Analysts believe this data release is just the latest of many pointing to the weakening UK and international economic picture.
“It is evident that manufacturers are now finding life much more difficult now compared with early 2011 and much of 2010,” said IHS Global Insight’s Howard Archer.
“Domestic demand is held back by tightening fiscal policy and a major squeeze on consumers, whilst a slowdown in growth is clearly limiting export orders appreciably.”
Overall output of production industries – including manufacturing, mining, electricity and water supply – increased by 0.2 per cent on a monthly basis in August.
However, industrial output in the three months to August was 0.6 per cent lower than in the same three months of 2010.