* Q3 GDP confirmed at 2.5 pct y/y, 0.2 pct q/q * Investment down 7.7 pct y/y, biggest fall in six years * Lower inflows of EU funds put lid on investment * Analysts say uncertainty also hindering investment (Adds detail, comment) By Marcin Goettig WARSAW, Nov 30 (Reuters) - Poland suffered its biggest contraction in investment for more than six years in the third quarter, data showed on Wednesday, as reduced inflows of European Union aid and political uncertainty discouraged firms from spending. Despite the drop in investment, the data confirmed that the economy had grown by 2.5 percent year-on-year thanks to a 3.9 annual rise in household consumption supported by a generous child benefit programme launched in April. The Polish economy grew by 3.1 percent in the second quarter. A breakdown of third-quarter growth published for the first time on Wednesday showed total consumption added 3.1 percentage points to the annual growth rate. Investment subtracted 1.4 percentage points and foreign trade shaved off a further 0.3 percentage points, while inventories added a 1.1 percentage point. Investment fell by 7.7 percent on an annual basis - its largest decline since the start of 2010, versus a 5 percent decline in the previous quarter, the data showed. The decline will disappoint Poland's ruling conservative, eurosceptic Law and Justice Party (PiS), which promised in last year's parliamentary election campaign to boost investment and push economic growth towards 5 percent. UNCERTAINTY "Companies are withholding investment due to the surrounding uncertainty, both domestic and external," said Monika Kurtek, chief economist at Bank Pocztowy. Export growth slowed to an annual 6.8 percent in the three months to September from 11.4 percent in the second quarter, reflecting weaker global trade following, among other factors, Britain's decision in June to exit the European Union. "One cannot expect that investment will turn positive in the fourth quarter ... but consumption may accelerate further," Kurtek said. Economists have said reduced inflows of EU funds are one of the main reasons for a slowdown in investment across central and eastern Europe. Economists have also said that increased uncertainty over policy in Poland has aggravated the decline in investment here. Since coming to power last year, PiS has been embroiled in a conflict with the constitutional court, introduced a new tax on bank assets and enacted a cut in the retirement age that was sharply criticised by economists. On Tuesday, Finance Minister Mateusz Morawiecki said Poland's $430 billion economy will likely grow by 2.5 percent to 3 percent this year, revising downward a previous forecast of 3.4 percent. The government initially forecast that Poland's economy would grow by 3.8 percent this year. (Additional reporting by Jakub Iglewski; Editing by Gareth Jones)