LONDON, Sept. 12 (Xinhua) -- Britain's economy showed uneven momentum in August as manufacturing and construction shrank again while services remained the only major sector still growing, survey data showed.

The manufacturing purchasing managers' index (PMI) slipped to 47 in August from 48 in July, S&P Global reported, marking an 11th straight month of contraction. Output dropped for a 10th month and new orders fell at their fastest pace in four months, with firms citing weak client confidence, higher labor costs and tariff uncertainties.

The construction industry posted an eighth month of decline, with its PMI rising slightly to 45.5 from July's 44.3 but staying well below the neutral 50 mark. Civil engineering, the weakest-performing segment in August, saw the sharpest fall since October 2020, with companies blaming tough market conditions, fierce price competition and sluggish domestic economic activities.

Services was the sole bright spot, with the PMI climbing to 54.2, the highest in 16 months, as new orders increased and business expectations strengthened. But the sector also showed strain: employment fell for an 11th consecutive month, and a survey by the Confederation of British Industry signaled continuing deterioration in confidence and activity in the quarter to August, with further declines in volumes and profits expected in the coming quarter.

Analysts warned of persistent headwinds. Rob Dobson of S&P Global Market Intelligence called the manufacturing outlook "very uncertain," noting that potential tax rises in the government's upcoming Budget could erode competitiveness.

Tim Moore of S&P Global Market Intelligence said construction faces its longest downturn since early 2020, with only 34 percent of the survey panel members expecting growth over the next year. CBI economist Alpesh Paleja pointed to rising employment costs as a key pressure forcing companies to cut hiring and investment.

The British Chambers of Commerce recently downgraded its 2025 forecast for business investment growth to 1.6 percent from 4.8 percent in its previous forecast, citing subdued sentiment and inflationary pressures.

John Bryson, professor of economic geography at the University of Birmingham, said Britain faces both external risks such as the U.S. tariff policies and geopolitical disputes and domestic factors, including tax burdens. These uncertainties are weighing on jobs, confidence as well as investment and consumer decisions, he added.