* FTSEurofirst 300 up 0.5 pct
* Publicis, Actelion, Sky, ARM rally after results
* Credit Suisse shares fall, brokers cite capital concerns
* Worries about ECB funding hit shares in Athens
* Additional inflows on horizon from investors - fund
By Lionel Laurent and Francesco Canepa
LONDON, April 21 (Reuters) - Positive company earnings updates pushed European shares higher on Tuesday, with the Greek stock market a standout loser as worries mounted about its banking sector.
Publicis, Sky and ARM Holdings closed between 3.9 and 6.2 percent higher after results.
European companies are heading for their best earnings season in four years, sharply outperforming U.S. counterparts on the back of a weak euro and improving economic conditions, driven by the European Central Bank's bond-buying stimulus plan.
"We will see a further run-up in markets ... We are seeing additional inflows from institutional clients," Union Investment portfolio manager Ingo Speich said.
The pan-European FTSEurofirst 300 index closed up 0.5 percent at 1,628.64 points, near multi-year peaks but having pared session gains as concerns about Greece capped sentiment.
The Athens ATG index fell 3.3 percent to its lowest since September 2012 after a Bloomberg report suggested the ECB had prepared a proposal to increase the haircut on the security that Greek banks offer in return for emergency liquidity.
The Greek banking index fell 3.8 percent.
Elsewhere, shares in Credit Suisse dropped 2.1 percent despite better-than-expected first-quarter earnings. While the stock has gained some 44 percent since mid-January, some brokers raised concerns over the bank's capital strength.
"The issue today will be capital for a bank where concerns linger," Jefferies analyst, Omar Fall, said.
A weak euro helped advertising group Publicis report forecast-beating organic sales growth in the first quarter, while Actelion, Europe's biggest biotech firm, raised its full-year guidance after strong sales of its new heart and lung drug helped profits beat expectations.
Associated British Foods, however, fell 5.3 percent after it lowering its full-year earnings guidance on currency concerns, sending its shares down more than 2 percent.
The two German listings of U.S. drugs group Mylan rose 9.4 percent and 6.4 percent respectively after it received a takeover offer from Teva.
Europe bourses in 2015: link.reuters.com/pap87v
Asset performance in 2015: link.reuters.com/gap87v
Today's European research round-up (Editing by Louise Ireland)