* FTSEurofirst 300 up 0.5 pct; hits 1 month intraday high
* Banks biggest gainers; EU to publish "stress test" in July
* 'Quadruple witching' expiries for futures and options
* For up-to-the minute market news, click on [
] By Harpreet BhalLONDON, June 18 (Reuters) - European shares were higher by mid-monrning on Friday, hitting a one-month intraday high and set to rise for an eighth straight session, following a late rally on Wall Street and with options and futures contracts set to expire.
By 0855 GMT, the pan-European FTSEurofirst 300 <
> index of top shares was 0.5 percent higher at 1,046.75 points, on track to post its longest winning streak in 11 months.However, a "quadruple witching" expiration of June stock, index futures and options boosted volatility for the index.
The FTSEurofirst 300 has added 6.3 percent in the past seven sessions, recouping some of the hefty loss from the past few months when fears of a debt contagion in the euro zone gripped investors.
"Despite low volumes, markets were quite strong in the last couple of days and that could indeed be a trigger for investors to effectively move back into equities," said Heino Ruland, strategist at Ruland Research.
The index is still down by 5.9 percent since the euro zone debt crisis surfaced in mid-April, but recent gains have helped it tip into positive territory for the year, up 0.1 percent.
Banks were among the biggest gainers, with Barclays <BARC.L> up 0.7 percent and Societe Generale <SOGN.PA> adding 2.2 percent.
In a move watched closely by financial markets, European leaders agreed on Thursday to publish details of "stress tests" showing the financial health of individual banks next month and to toughen budget rules to restore confidence in their currency union. [
]"The outcome (of the stress test) can only be positive because then we will know who is a reliable partner and who is not," Ruland said.
"Having more transparency will effectively reduce the intermediate status of the European Central Bank and interbank lending will resume."
Spanish bank Santander <SAN.MC>, meanwhile, confirmed it had made an offer for around 300 British branches of Royal Bank of Scotland <RBS.L>. Santander was up 2.4 percent, while RBS gained 1 percent.
ROCHE UNDER PRESSURE
Among individual movers, Roche <ROG.VX> fell 2.3 percent after a promising new diabetes drug it is developing under license from France's Ipsen <IPN.PA> faced a delay of at least 12 to 18 months after hypersensitivity problems were seen in some patients. [
]News of the delay boosted rival Novo Nordisk <NOVOb.CO>, the world's biggest diabetes drug producer, which rose 3.5 percent. [
]A relief rally in BP's <BP.L> shares gathered pace, with the stock up 3.4 percent, adding to the previous session's gains.
The oil major's bosses have weathered a week of anger in Washington but the energy giant's financial outlook faces renewed scrutiny from investors trying to gauge remaining costs and risks from the biggest oil spill in U.S. history. [
]Across Europe, Britain's FTSE 100 <
>, Germany's DAX < > and France's CAC 40 < > advanced 0.1 to 0.4 percent.The Thomson Reuters Peripheral Eurozone Countries Index <.TRXFLDPIPU> rose 0.6 percent. (Editing by Hans Peters)