LONDON, Dec 18 (Reuters) - European shares fell on Friday to retreat from a one-week high reached in the previous session, with supermarket group Casino losing more ground in the wake of a negative research note on it.
The pan-European FTSEurofirst 300 index, which had risen 1.3 percent on Thursday, fell 0.6 percent, while the euro zone's blue-chip Euro STOXX 50 index also weakened 0.8 percent.
Weak oil prices put pressure on the shares of energy companies, which in turn weighed on equities.
Shares in French company Casino also fell 3.8 percent, extending losses from an 11.5 percent slump on Thursday after research firm Muddy Waters said Casino was one of the "most overvalued and misunderstood" companies it had come across.
Casino said on Thursday that the report contained "grossly erroneous allegations" that the group would answer in detail. (Reporting by Sudip Kar-Gupta; Editing by Atul Prakash)