UK stocks declined on Wednesday ahead of a Federal Reserve policy decision, as negative news from Greece continued to weigh on sentiment.Just before noon, the FTSE 100 was trading 0.31% lower at 6,689.07 after settling at 6,710.10 on Tuesday, its lowest close since 10 March.Should the index finish Wednesday's session below the 6,700 mark, it would mark its worst close since mid-January.Ongoing developments in the Greek debt crisis continue to be in focus for the markets as concerns about a potential 'Grexit' grow, with Athens continuing to butt heads with its creditors.Greek Prime Minister Alexis Tsipras has launched a scathing attack on the IMF in particular, saying the fund bears "criminal responsibility" for his country's financial problems.His comments came as UK Chancellor George Osborne revealed that Whitehall had stepped up its contingency planning in case of Greece leaves the euro. Osborne warned people not to "underestimate the potential damage to financial confidence" from a Grexit.Fears over a possible 'Grexit' offset positive unemployment data, as UK hourly earnings grew more than expected in the three months to April.According to the Office for National Statistics, the average hourly earnings, including bonus, rose 2.7% year-on-year in the period, exceeding expectations calling for a 2.1% increase.The unemployment rate remained at 5.5%, its lowest level since 2008.Meanwhile, the two-day Federal Open Market Committee meeting comes to an end on Wednesday evening and will likely to steal the spotlight with investors looking out for possible hints about the first rate hike.Analysts generally don't expect the Fed to tighten monetary policy at this month's meeting in light of recent mixed data on the US economy.Supermarkets declineProperty developer Berkeley Group impressed investors after posting a 44.6% jump in full-year pre-tax profit to £423.5m. The company said domestic demand was strong in its core markets of London and the south of England, and the developer has experienced sales price increases in line with those reported in the wider market.Betfair declined despite meeting analysts' forecasts with a 53% rise in full-year operating profit as product and marketing investment drove record customer activity. Broker Numis raised its rating on the stock from 'sell' to 'reduce', but said its valuation was still "too high".High street sports retailer JD Sports Fashion edged lower despite saying it expects to meet annual forecasts after a solid start to the year. However, the company did note tough comparatives with the previous year and weaker margins in Europe.Supermarket rivals Morrisons, Sainsbury's and Tesco fell after Credit Suisse initiated coverage of the sector with a negative stance. The bank said it sees few opportunities within a group that has historically mis-allocated capital, is faced with extreme competitive pressures and operates in a low-growth environment.Royal Bank of Scotland edged lower after admitting that some 600,000 transactions had gone 'missing' with payments not being deposited in a number of accounts overnight.The FTSE 100 group said the transaction affected customers at Natwest, Ulster Bank, Coutts and RBS.Market MoverstechMARK 3,142.82 -0.34%FTSE 100 6,680.32 -0.44%FTSE 250 17,678.76 -0.32%FTSE 100 - RisersCRH (CRH) 1,850.00p +1.15%Lloyds Banking Group (LLOY) 86.59p +1.04%Centrica (CNA) 270.00p +0.97%Wolseley (WOS) 4,148.00p +0.66%Persimmon (PSN) 1,971.00p +0.61%BT Group (BT.A) 447.90p +0.60%SSE (SSE) 1,596.00p +0.57%Barratt Developments (BDEV) 612.50p +0.49%BG Group (BG.) 1,086.00p +0.46%Smiths Group (SMIN) 1,134.00p +0.44%FTSE 100 - FallersExperian (EXPN) 1,184.00p -2.47%Land Securities Group (LAND) 1,247.00p -1.66%Marks & Spencer Group (MKS) 538.00p -1.65%Tesco (TSCO) 208.00p -1.65%British Land Company (BLND) 819.50p -1.62%Intu Properties (INTU) 315.00p -1.56%Weir Group (WEIR) 1,781.00p -1.49%London Stock Exchange Group (LSE) 2,312.00p -1.49%Morrison (Wm) Supermarkets (MRW) 175.10p -1.41%Hikma Pharmaceuticals (HIK) 1,888.00p -1.41%FTSE 250 - RisersBerkeley Group Holdings (The) (BKG) 3,410.00p +7.98%Imagination Technologies Group (IMG) 232.50p +4.97%Infinis Energy (INFI) 195.00p +2.63%Tullow Oil (TLW) 369.10p +1.96%Fisher (James) & Sons (FSJ) 1,350.00p +1.81%Soco International (SIA) 189.20p +1.45%Ocado Group (OCDO) 381.10p +1.36%NMC Health (NMC) 800.50p +1.33%Daejan Holdings (DJAN) 5,685.00p +1.25%Cairn Energy (CNE) 183.20p +1.16%FTSE 250 - FallersJust Eat (JE.) 400.10p -5.23%Betfair Group (BET) 2,432.00p -3.26%Kaz Minerals (KAZ) 225.10p -2.97%Amlin (AML) 473.50p -2.49%Nostrum Oil & Gas (NOG) 540.00p -2.35%Fidessa Group (FDSA) 2,206.00p -2.17%Laird (LRD) 376.50p -2.03%St. Modwen Properties (SMP) 449.60p -1.86%Spire Healthcare Group (SPI) 324.00p -1.82%Indivior (INDV) 229.30p -1.67%FTSE TechMARK - RisersUCW Limited (UCW) A$0.02 +26.67%Promethean World (PRW) 34.00p +24.77%Anite (AIE) 127.50p +23.79%Spirent Communications (SPT) 93.50p +5.95%BATM Advanced Communications Ltd. (BVC) 15.50p +5.08%Innovation Group (TIG) 32.75p +3.97%NCC Group (NCC) 218.00p +2.83%CML Microsystems (CML) 389.50p +2.63%SDL (SDL) 415.50p +1.84%RM (RM.) 150.00p +1.69%FTSE TechMARK - FallersOxford Biomedica (OXB) 8.20p -3.07%Triad Group (TRD) 22.00p -2.22%Torotrak (TRK) 7.60p -1.94%Consort Medical (CSRT) 938.00p -0.95%Dialight (DIA) 541.00p -0.55%KCOM Group (KCOM) 97.50p -0.51%Sepura (SEPU) 159.00p -0.47%