(Reuters) - Asian shares edged up Tuesday as investors held on to hopes the European Central Bank will act to soothe borrowing costs, even as officials denied a report about the shape of its planned bond buying strategy.

MSCI's broadest index of Asia-Pacific shares outside Japan <.MIAPJ0000PUS> added 0.2 percent while Japan's Nikkei stock average <.N225> opened down 0.1 percent after rising to a three-month high on Monday. .T

U.S. stocks were flat on Monday, pausing after a six-week rise, but Apple Inc (AAPL.O) hit a new high to become the world's most valuable public company while the Standard & Poor's 500 index .SPX hovered near a four-year peak. Europe's top shares fell.

"There was no movement in the New York markets. Today's market will be very cautious and uncertain," said Takashi Hiroki, chief strategist at Monex Inc, of Japanese stocks.

The ECB said on Monday it was misleading to talk about decisions not yet taken, denying a weekend report which said the bank is considering buying the bonds of struggling euro zone countries when their yield spreads hit a certain level over German bonds.

The Bundesbank also kept its opposition to the ECB buying euro zone sovereign bonds, even after German Chancellor Angela Merkel voiced support for the ECB's crisis-fighting strategy last week.

"Strictly limited and highly conditional support by the ECB is unlikely to provide an early resolution of the financial stress that confronts 'peripheral' European sovereigns," Barclays Capital said in a research note.

"For now, however, investors seem to be adopting a hopeful rather than skeptical stance," it said.

Global stocks and the euro closed almost flat on Monday. Oil and U.S. Treasury prices also hugged their break-even point, while Spanish sovereign bonds rallied and lowered their yields further from critically high levels.

"In a broader sense investors continue to respond favorably to coordinated global central bank intervention, part of which is the ability to successfully jawbone markets into the belief that whatever they have up their sleeves, central bankers will trump all," said Andrew Wilkinson, chief economic strategist at Miller Tabak & Co.

After a couple of weeks of summer lull, markets will brace for major events including the ECB's policy meeting on September 6 and a meeting of euro zone finance ministers in mid-September.

Leaders of Germany, France, the Eurogroup and Greece are meeting bilaterally this week, with German Chancellor Angela Merkel and Greek Prime Minister Antonis Samaras holding a dialogue on Friday over Greece's rescue plans ahead of a visit to Greece next month by global lenders to finalize their assessment of Athens' austerity reforms.

The dollar traded down 0.1 percent at 79.32 yen, retreating from a five-week high against the yen at 79.660 yen hit on Monday. The euro inched up 0.1 percent to $1.2354.

Asian credit markets firmed, with the spread on the iTraxx Asia ex-Japan investment-grade index tightening by 2 basis points.

Oil was mixed, with Brent up 0.1 percent at $113.78 a barrel while U.S. crude futures eased 0.1 percent to $95.91 a barrel.

As lackluster stock market returns and historically low interest rates have made it difficult for pensions to earn a enough return, many of the largest U.S. public pensions have raised their exposure to alternative investments to record levels this year, ranging from Polish energy facilities to catastrophe bonds.

(Additional reporting by Dominic Lau in Tokyo; Editing by Richard Pullin)

Apple inc. Barclays Japan Germany