London open: Stocks inch higher ahead of data, but Greek worries persist

After an initial drop, London's Footsie bounced into positive territory on Tuesday morning, though gains were only modest as investors awaited key economic data and reacted to uncertainty in Greece.Reports that Athens is preparing for a debt default if it can't reach a deal with its creditors were likely limiting upside for markets, especially with stocks already trading near record highs.The FTSE 100 was up 0.17% at 7,076.44 after the opening hour.The index had fallen to 7,064.30 the previous session as it pulled back from the all-time closing high of 7,089.77 reached on Friday.The UK consumer price index is due for release at 09:30 and is expected to remain unchanged at zero in March, though some analysts predict Britain could fall into deflation for the first time since 1960."It wouldn't surprise at all to see -0.1% given the way food prices have continued to fall as the discount supermarkets continue to push prices lower, while the recent 5% price cuts by British Gas are likely to feed into energy bills for March," said analyst Michael Hewson from CMC Markets.Meanwhile, US retail sales at 13:30 are forecast to have risen by 1% in March after a 0.6% decline in February.Greece on Monday evening denied a report in the Financial Times that cited a government official as saying that there is "no alternative" to a default if Athens does not reach a deal with its lenders. The paper said Greece was withholding €2.5bn of payments due to the International Monetary Fund in May and June if no agreement is made."Greece [...] is not preparing for any debt default and the same goes for its lenders. Negotiations are proceeding swiftly towards a mutually beneficial solution," the office of prime minister Alexis Tsipras said in a statement.Tullow Oil jumps on upgrade, miners reboundTullow Oil's share price surged early on after Citigroup raised its rating on the stock from 'neutral' to 'buy', saying that the oil group's portfolio quality was "undervalued" by the market.Mining stocks were putting in a decent performance, rebounding after heavy losses on Monday when a number of investment banks shaved their price targets for iron ore over the coming years. BHP Billiton, Rio Tinto, Glencore and Anglo American were all in demand.Also higher was Poundland after a trading update showed the discount retailer had topped a billion pounds of annual sales for the first time with revenue in final quarter excluding the Spanish business up 6.5%.Mark Hodges, the former board member and head of UK operations at Aviva, has been named as the new managing director at British Gas, causing shares in owner Centrica to rise.British Land gained after buying the One Sheldon Square building for £210m to extend its Paddington Central development in London.Energy services company Wood Group gained after securing a new five-year contract with UK exploration and production outfit Enquest in the North Sea.UK hospital operator Spire Healthcare dropped sharply after private equity group Cinven sold down its stake to 38.3% with a £136m share sale. Cinven sold 40.1m shares at 340p each, compared with Monday's closing price of 367p.Market MoverstechMARK 3,259.67 -0.04%FTSE 100 7,076.44 +0.17%FTSE 250 17,847.03 +0.10%FTSE 100 - RisersBHP Billiton (BLT) 1,439.00p +1.62%Barclays (BARC) 263.60p +1.60%Glencore (GLEN) 289.20p +1.42%Rio Tinto (RIO) 2,851.50p +1.33%Anglo American (AAL) 1,010.50p +1.18%Royal Bank of Scotland Group (RBS) 357.00p +1.08%Aggreko (AGK) 1,590.00p +1.02%ARM Holdings (ARM) 1,174.00p +0.95%Aviva (AV.) 566.00p +0.80%Royal Dutch Shell 'B' (RDSB) 2,080.50p +0.73%FTSE 100 - FallersAberdeen Asset Management (ADN) 495.60p -2.15%Shire Plc (SHP) 5,580.00p -1.76%Associated British Foods (ABF) 2,953.00p -1.24%Barratt Developments (BDEV) 547.00p -1.00%Admiral Group (ADM) 1,579.00p -0.82%SABMiller (SAB) 3,608.50p -0.74%Pearson (PSON) 1,434.00p -0.62%Hargreaves Lansdown (HL.) 1,230.00p -0.57%BAE Systems (BA.) 533.50p -0.56%G4S (GFS) 304.70p -0.55%FTSE 250 - RisersTullow Oil (TLW) 359.20p +5.80%Hunting (HTG) 574.00p +3.24%Premier Oil (PMO) 160.10p +3.09%Enterprise Inns (ETI) 113.80p +2.99%Vedanta Resources (VED) 532.00p +2.80%Poundland Group (PLND) 340.00p +2.41%Indivior (INDV) 224.90p +2.27%Ophir Energy (OPHR) 163.20p +1.75%Drax Group (DRX) 414.90p +1.69%Kaz Minerals (KAZ) 223.40p +1.68%FTSE 250 - FallersSpire Healthcare Group (SPI) 335.70p -8.55%AL Noor Hospitals Group (ANH) 921.50p -7.15%Card Factory (CARD) 311.10p -2.84%Allied Minds (ALM) 713.50p -1.59%Fidelity China Special Situations (FCSS) 167.20p -1.53%Home Retail Group (HOME) 172.20p -1.26%Brewin Dolphin Holdings (BRW) 318.10p -1.24%Nostrum Oil & Gas (NOG) 601.50p -1.23%NMC Health (NMC) 683.00p -1.16%Polar Capital Technology Trust (PCT) 594.50p -1.16%