* FTSEurofirst falls back 0.5 pct, Euro STOXX down 0.8 pct
* Athens market down 2.2 pct after Monday's 16 pct fall
* Worries over stalled reforms hit Credit Agricole shares
* BMW down as earnings momentum slows
* Continental AG rises after hiking outlook (Adds detail)
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, and energy stocks hit by weak oil prices.
The pan-European FTSEurofirst 300 index was down 0.5 percent at 1,576.27 at 1230 GMT, while the euro zone's blue-chip Euro STOXX 50 index was down 0.8 percent.
Athens' stock market, which slumped 16 percent on Monday after a five-week shutdown, fell a further 2.2 percent. Greece has had to introduce capital controls and is seeking a new bailout deal following a debt crisis.
Many investors have cut their exposure to Greece, which accounts for only a fraction of the overall European economy, and are focusing more on "core" European markets such as Germany and France, or Spain and Italy in the south.
Falls in Credit Agricole and BMW helped push the French and German markets lower on Tuesday.
Credit Agricole fell 11 percent after the bank ruled out any near-term simplification of its structure due to "constraints" encountered during talks with the European Central Bank (ECB).
BMW dropped 2.3 percent after its second quarter operating profit eased back on slowing China sales, leading BMW to warn that, while it still expects 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 hit companies with strong business ties to the region, such as European carmakers and luxury goods firms, as well as mining and oil stocks. 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, with traders citing a downgrade on it from Bank of America Merrill Lynch, but tyremaker Continental rose 5.1 percent after hiking its profit outlook.
Spain's Abengoa fell 11.9 percent, with B-shares down 16.5 percent as selling continues following a surprise rights issue.
The B-shares of the troubled energy firm, which are contained in Spain's blue-chip IBEX index, are down more than 40 percent in the last two sessions.
Europe bourses in 2015: link.reuters.com/pap87v
Asset performance in 2015: link.reuters.com/gap87v
Today's European research round-up (Additional reporting by Alistair Smout; Editing by Andrew Heavens)