* FTSEurofirst 300 down 0.5 pct after touching seven-year high
* Tullow Oil down on speculation over potential FTSE 100 exit
* Vivendi falls after plan to sell stake in Numericable
By Atul Prakash
LONDON, March 2 (Reuters) - Europe's FTSEurofirst 300 index retreated from a seven-year high on Monday, with Tullow Oil down on concerns that it could be dropped from Britain's blue-chip index after a quarterly reshuffle and Vivendi falling after a stake disposal.
Greek banks also came under pressure from lingering concerns over its debt repayment plans.
Tullow Oil slid 6.8 percent to feature among the top fallers on the FTSEurofist 300 on concerns the stock could be replaced on Britain's FTSE 100 index by Hikma Pharmaceuticals this month, traders said.
"Investors are worried that a likely drop from the FTSE will prompt tracker funds and some exchange-traded funds to sell Tullow Oil shares to reduce their weightings," Jawaid Afsar, trader at Securequity, said.
Vivendi fell 5.1 percent after the French media group agreed to sell its remaining stake in Numericable-SFR to Altice at a price analysts and traders viewed as low. Vivendi slipped despite announcing a share buyback at a maximum purchase price of 20 euros a share.
Numericable rose 6.4 percent and Altice was up 6.7 percent.
Analysts said they were also disappointed by the small scale of the share buyback Vivendi announced along with its fourth-quarter results on Friday.
"While Vivendi has simplified its portfolio considerably, the comments on cash return disappointed, especially what (seems to us) an unnecessary limit on the price at which the shares are bought back," analysts at Liberum said, downgrading the stock to hold from buy.
The FTSEurofirst 300 was down 0.5 percent at 1,556.26 points by 1211 GMT after rising to 1,567.68, the highest level since late 2007.
The index was also pressured by Greek banks, with the sector index falling 7.6 percent and lenders National Bank of Greece, Piraeus Bank and Alpha Bank down 6.7 to 8.9 percent on uncertainty over debt repayments.
Greece called into question on Saturday a debt payment it must make to the European Central Bank this summer after acknowledging that it faces problems in meeting its obligations.
German Finance Minister Wolfgang Schaeuble urged Greece to implement its reform plan if it wants to secure future help from abroad. (Additional reporting by Francesco Canepa; Editing by David Goodman)