* Athens' ATG falls 1.7 pct, underperforms FTSEurofirst 300
* Tech shares outperform on M&A activity in sector
* Sweden's Fingerprint Cards surges nearly 20 pct
* Europe bourses in 2015: link.reuters.com/pap87v
* Asset performance in 2015: link.reuters.com/gap87v
By Sudip Kar-Gupta
LONDON, May 28 (Reuters) - European shares retreated on Thursday, as lingering uncertainty over Greece's debt problems held back the region's stock markets.
European equities had rallied on Wednesday on reports of a staff-level agreement between Greece and its creditors, until German Finance Minister Wolfgang Schaeuble said not much progress had been made.
Athens' benchmark ATG equity index closed down 1.7 percent, underperforming a 0.5 percent decline on the pan-European FTSEurofirst 300 index. The ATG is up 1.4 percent since the start of 2015, compared with an 18 percent gain for the FTSEurofirst.
Desperate to get more funds before it runs out of cash, the Greek government has alternated between lashing out at its creditors, especially the International Monetary Fund, and declaring a deal is just around the corner.
Most investors expect Greece to remain within the euro zone even if it misses some payments.
Record-low interest rates and other economic stimulus measures by the European Central Bank have helped European stocks to rally this year. But traders said the lack of progress over Greece was making some investors wary.
"Overall sentiment remains neutral with markets likely to be confined to range-trading as traders are remaining on the sidelines listening out for new developments where Greece is concerned," said Markus Huber, senior sales trader at Peregine & Black.
Mike Reuter, a trader at brokerage Tradition, also said the Greek stalemate could cause more market weakness on Friday.
However, European technology shares outperformed, boosted by takeover speculation after Reuters reported that Avago Technologies was close to an agreement to buy Broadcom.
European chip-makers Infineon and STM rose 3.2 percent and 3.3 percent, respectively.
Swedish technology company Fingerprint Cards also surged nearly 20 percent, as traders speculated that a Google event would highlight growing interest in fingerprint recognition technology in general.
Today's European research round-up (Editing by Larry King)