Persistent worries over the world economy, fueled by tepid U.S. data and a relatively lackluster start to the earnings season, kept a lid on equity gains on Friday, boosting safe-haven trades like the dollar and yen.

Growing jitters over the struggling Greek economy are weighing on the euro zone, with the single currency down almost one percent versus the dollar while the uncertain U.S. economic picture saw oil prices falling for the fifth day in a row.

Upbeat earnings from chipmaker Intel Corp gave an initial leg-up to share prices -- with Asian tech-heavy bourses like Seoul seeing strong gains -- but the momentum petered out as doubts about the strength of the U.S. recovery weighed.

By 0930 GMT, world stocks <.MIWD00000PUS> were just above flat, staying off 15-month highs hit earlier in the week. Earlier Japan's Nikkei <.N225> closed at a 15-month high, thanks to gains for tech firms like chipmaker Tokyo Electron <8035.T>.

European stock markets opened firmer on back of the Intel results, extending their winning streak to three sessions.

The FTSEurofirst <.FTEU3> index of top European shares rose 0.6 percent, with banks accounting for most of the gains. HSBC , Santander and Deutsche rose up to 1.4 percent on hopes of good news from investment bank JPMorgan when it reports fourth quarter earnings at 1200 GMT.

Results will dominate the newsflow and I would expect good numbers, but there will be little share price reaction unless companies increase expectations for the outlook, which they have little incentive to do, said Lars Kreckel, strategist at Exane BNP Paribas in London.

Reflecting these worries, U.S. stock futures slipped 0.2 percent. Wall Street closed only marginally higher on Thursday, weighed down by weak U.S. retail sales data and a rise in jobless claims.

Corporate earnings alone will not lift markets for long, said Geoff Lewis, head of investment services at JP Morgan Asset Management in Hong Kong.

You still have to see continued good news on the economic front to validate improvements in corporate earnings forecasts, said. Markets will want to see evidence of strength in private sector demand ... it's important the economy stand on its feet after the public fiscal stimulus starts to fade.

Investors now await U.S. CPI and manufacturing data due at 1330 GMT and 1415 GMT respectively.

DOLLAR, YEN, BONDS GAIN

With investors reluctant to take on too much risk, the U.S. dollar <.DXY> and yen rose.

Against a currency basket, the dollar <.DXY> rose half a percent to 77.115 but against the yen it fell 0.4 percent to 90.66 yen, its lowest in nearly four weeks.

The euro traded at a four-week low versus yen, down 1.2 percent.

The single currency is taking a hit from Greece. Its weakness has deepened after comments on Thursday by European Central Bank President Jean-Claude Trichet who warned Europe faced a major debt problem and that no government could expect special treatment from the ECB.

If we see strong U.S. data later today, the dollar will rise, if it's weak the euro will rise. It's a fairly reactionary market today, said Peter Frank, currency strategist at Societe Generale in London.

U.S. Treasuries were up, soothed by a solid auction of 30-year bills on Thursday.

Oil however weakened and was set for its first weekly drop in more than a month.

(Additional reporting by Naomi Tajitsu and Simon Falush in London; Umesh Desai in Hong Kong, editing by Mike Peacock)

Japan Nikkei 225