* FTSEurofirst falls back 0.5 pct, Euro STOXX down 0.6 pct
* Athens market down 4 pct after slumping 16 pct on Monday
* Worries over stalled reforms hit Credit Agricole shares
* BMW down as earnings momentum slows
By Sudip Kar-Gupta
LONDON, Aug 4 (Reuters) - European stock markets lost ground on Tuesday, with French bank Credit Agricole and German carmaker BMW among the worst performers after reporting results, while weak oil prices also weighed on energy stocks.
The pan-European FTSEurofirst 300 index, which had risen 0.7 percent on Monday, fell back by 0.5 percent while the euro zone's blue-chip Euro STOXX 50 index also weakened by 0.6 percent.
The Athens stock market, which had slumped 16 percent on Monday after re-opening following a five-week shutdown, fell a further 4 percent on Tuesday as the country grapples with debt and economic problems.
Many investors have cut their exposure to Greece, which accounts for only a fraction of the overall European economy, and are focusing more on the state of "core" European markets such as Germany and France.
Falls in Credit Agricole and BMW contributed to the French and German markets slipping back on Tuesday.
Credit Agricole slumped 8 percent after it booked an additional 350 million euros in litigation provisions while posting second quarter results. Traders also expressed disappointment with the fact that Agricole had put certain structural reforms on hold.
BMW also fell 2.7 percent after its second quarter operating profit eased 3 percent on slowing China sales, leading the carmaker to caution that while it still expects new records for sales and pretax profit in the full year, earnings momentum was slowing.
"China is still a concern, and we're still not seeing top-line growth in a lot of the earnings releases that are coming through," said Terry Torrison, managing director at McLaren Securities in Monaco.
Concerns about China's economy have had an impact on companies with strong business ties to the region, such as European carmakers and luxury goods companies, as well as mining and oil stocks due to the fact that China is a leading global user of commodities.
Oil prices recovered slightly on Tuesday after a sharp drop in the previous session, but a weakening economic outlook in Asia prompted analysts to warn of further falls, and the STOXX Europe 600 Oil & Gas Index fell 1 percent.
German airline Lufthansa declined 3.5 percent as traders cited a downgrade on it from Bank of America Merrill Lynch, but tyremaker Continental rose 3.9 percent after hiking its profit outlook.
According to data from Thomson Reuters StarMine, 58 percent of the companies on the pan-European STOXX 600 index have met or beaten market expectations with their results so far this quarter.
However, the results so far have shown a 0.9 percent fall in earnings compared to a year ago, the StarMine data shows.
Europe bourses in 2015: link.reuters.com/pap87v
Asset performance in 2015: link.reuters.com/gap87v
Today's European research round-up (Editing by Alison Williams)