* Sterling eases from 2-week high versus dollar * Strong resistance at $1.5912, barriers cited at $1.5950 * Euro higher versus sterling on ECB optimism LONDON, Sept 4 (Reuters) - Sterling eased from a two-week high against the dollar on Tuesday after UK construction sector data disappointed, though optimism that the European Central Bank would take measures to stem the region's debt crisis checked losses. The euro zone is the UK's biggest trading partner and any easing of the crisis is seen as positive for sterling, especially against the dollar. The ECB meets on Thursday and is widely expected to announce a bond buying programme aimed at lowering borrowing costs for Spain and Italy. Against the dollar, sterling fell from a two-week high of $1.5909 to trade at $1.5890, barely changed on the day. Traders cited resistance at its August 23 high of $1.5912 with some expecting it to test that level if demand for riskier assets and currencies perked up. Sterling has been underpinned in recent sessions by some better-than-expected UK data, especially from the manufacturing sector and growing bets that the U.S. Federal Reserve would launch another round of easing in the coming months. Data on Tuesday showed British construction activity fell unexpectedly last month as new orders slumped at the fastest pace since the height of the 2008-2009 financial crisis. . "This would suggest even more elongated contraction in the construction sector," said Lee McDarby, head of dealing at Investec Corporate Treasury. "The pound may have taken a bit of a blow to the ribs but it still currently cannot decide which side of $1.59 to trade against the dollar." The construction data came just a day after a stronger-than-forecast manufacturing industry survey prompted market players to take a slightly brighter view of the UK economy, which is mired in recession. All eyes will now be on the services sector PMI due on Wednesday, which is expected to show a slight improvement in activity. The services sector contributes the bulk of UK gross domestic product and a better-than-expected number could lift the pound. Against the euro, though, the pound lagged. The common currency was up 0.1 percent at 79.35 pence. The euro was trading near a two-month high against the dollar, bolstered by latest comments from ECB chief Mario Draghi who said central bank purchases of sovereign bonds of up to three years maturity did not constitute state aid. Those comments have boosted expectations that he may announce a bond-buying plan as early as Thursday. The Bank of England also meets on Thursday, although policymakers are expected to keep interest rates and the quantitative easing total unchanged. They are expected to keep policy unchanged until towards the end of the year. Analysts say consumer spending is still sluggish, keeping alive chances of more stimulus from the BoE. The British Retail Consortium said overnight that the London Olympics failed to boost retail sales as hoped last month, as households preferred to watch the games rather than go shopping, giving stores one of their worst months of 2012.

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