* Sentix Aug index plummets to -13.5 pct vs 5.3 in July
* Fastest dip on record; lowest level since Sept 2009
* Unease over policy response to euro, U.S. debt crises
* Sentix sees recession 'on its way'
By Sarah Marsh
BERLIN, Aug 8 (Reuters) - Euro zone investor sentiment plummeted going into August, hitting its lowest level since September 2009 amid concerns global policymakers lack the tools to respond effectively to a deepening economic crisis, a survey showed.
Market research group Sentix said on Monday its headline index fell at its fastest pace on record to -13.5 in August from 5.3 in July, missing even the lowest forecast in a Reuters survey of economists for a drop to -1.0 by a long way.
Economists had on average forecast a fall to 1.9.
"The mix of EU debt problems, the powerlessness of policymakers regarding this and the quarrels in the U.S. regarding lifting the deficit ceiling have strongly unsettled investors," Sentix said in a statement.
The group said this mix of problems, as well as an historic downgrade of the U.S. credit rating and turbulence on the financial markets, were reinforcing the impression that the outlook for the global economy was darkening.
A sub-index of current conditions fell to 3.50 from 19.25, while expectations dropped to -29.00 from -7.75.
"Ever more investors see a spillover of the financial markets' problems into the real economy as a probable scenario," Sentix said.
Twin debt crises in Europe and the United States are stoking fears of the rich world sliding back into recession, and finance chiefs from the world's industrial powers pledged on Sunday to take whatever actions were needed to steady markets in an attempt to calm frazzled investors' nerves.
The market reaction was mixed on Monday. Asian bourses were still coloured red, but European shares rose and debt spreads eased, reassured by signs the European Central Bank had stepped up its support measures by buying Italian and Spanish debt.
"Countries' fragile financial framework is causing many investors to question how states and central banks can even tackle a possible recession," Sentix said, adding: "A global recession is giving notice that it is on its way".
Sentix based its data on a survey of 822 European private and institutional investors conducted between August 4 and August 6.
(Editing by John Stonestreet)