UK stocks fell on Monday morning on the back of renewed concerns about Greece, while investors digested the latest trade data from China and Germany.London's FTSE 100 was down 0.55% at 6,873.61 within the opening hour of trade.Greece's new government has threatened that they could call a referendum or have early elections if the Eurozone rejects its proposed reforms."We are not attached to our posts. If needed, if we encounter implacability, we will resort to the Greek people either through elections or a referendum," said finance minister Yanis Varoufakis.According to economist Christian Schulz from Berenberg, Athens "continues to severely damage the trust of its Eurozone partners, the only viable source of short-term funding to keep Greece afloat and in the euro".In economic data, China's trade surplus rose to a record $60.62bn in February, compared with $60bn in January. This increase came after a 48.3% year-on-year surge in exports and a 20.5% drop in imports, compared with expectations of +14% and -10% respectively.However, due to the distortions resulting from the lunar new year holiday, analysts focused on figures for the past two months which show a slightly less volatile picture - exports over January and February combined were up 15% on last year, while imports declined 20%."Trade growth is highly volatile at the start of the year due to shifts in the timing of Chinese New Year, which disrupts manufacturing activity as migrant workers return home but also leads to a pre-holiday rush to complete outstanding export orders," according to analysts at Capital Economics.The widening seen in the surplus and rise in exports was generally well ahead of economists' expectations but the decline in imports is another sign pointing to a slowing in the Chinese economy as a result of reduced domestic demand.Meanwhile, the German trade surplus shrank to €19.7bn in January from €21.6bn the month before as exports fell 2.1% and imports declined 0.3%.Property stocks take a hitReal estate investment trusts such as Land Securities, British Land and Intu Properties were among the worst performers on the Footsie early on, while second-tier peers St Modwen Properties and Capital & Counties also weakened.St Modwen in particular was feeling the effects of a downgrade to 'neutral' at JPMorgan Cazenove.WPP, the world's biggest advertising company, declined despite beating expectations with a record £1.5bn annual profit in 2014, up 12% on the previous year. Revenues were up nearly 5% at £11.6bn, though currency movements weighed on growth.Mining stocks were mostly higher on the back of strong export data from top metals consumer China. Glencore, Randgold and Frensillo were all on the rise.However, shares in Antofagasta were flat after saying that ongoing protests at its Los Pelambres copper project in Chile have reduced copper production by 5,000 tonnes over the last two weeks.ITV rose after Westhouse Securities upgraded the stock to 'add', G4S was lifted by a Deutsche Bank upgrade to 'hold', while Reckitt Benckiser was boosted to 'buy' at Jefferies.Market MoverstechMARK 3,144.08 -0.71%FTSE 100 6,873.61 -0.55%FTSE 250 17,188.67 -0.48%FTSE 100 - RisersStandard Chartered (STAN) 1,038.50p +1.42%Randgold Resources Ltd. (RRS) 4,645.00p +1.40%Fresnillo (FRES) 705.50p +1.00%Glencore (GLEN) 291.75p +0.78%ITV (ITV) 248.10p +0.65%G4S (GFS) 297.20p +0.64%Rolls-Royce Holdings (RR.) 993.00p +0.61%Tullow Oil (TLW) 355.00p +0.51%Meggitt (MGGT) 559.50p +0.45%HSBC Holdings (HSBA) 569.50p +0.26%FTSE 100 - FallersLand Securities Group (LAND) 1,235.00p -2.37%British Land Co (BLND) 823.50p -1.91%United Utilities Group (UU.) 908.00p -1.84%Kingfisher (KGF) 356.70p -1.84%RSA Insurance Group (RSA) 411.00p -1.67%Marks & Spencer Group (MKS) 502.50p -1.66%Aviva (AV.) 554.00p -1.60%Friends Life Group Limited (FLG) 422.70p -1.58%Smith & Nephew (SN.) 1,126.00p -1.57%Barratt Developments (BDEV) 511.00p -1.54%FTSE 250 - RisersInfinis Energy (INFI) 196.80p +2.56%Vedanta Resources (VED) 583.50p +2.19%IP Group (IPO) 243.10p +2.14%Ophir Energy (OPHR) 140.60p +2.11%Soco International (SIA) 261.30p +1.99%JD Sports Fashion (JD.) 501.50p +1.85%PayPoint (PAY) 842.50p +1.44%Bank of Georgia Holdings (BGEO) 1,847.00p +1.32%Supergroup (SGP) 940.50p +1.29%Hunting (HTG) 504.00p +1.27%FTSE 250 - FallersAllied Minds (ALM) 550.00p -4.93%St. Modwen Properties (SMP) 446.80p -3.48%Capital & Counties Properties (CAPC) 398.00p -2.57%Man Group (EMG) 189.90p -2.37%Workspace Group (WKP) 830.00p -2.35%Riverstone Energy Limited (RSE) 1,009.00p -1.94%Evraz (EVR) 189.90p -1.91%Spire Healthcare Group (SPI) 318.90p -1.88%Hansteen Holdings (HSTN) 114.60p -1.72%NMC Health (NMC) 602.00p -1.71%