* FTSEurofirst 300 up 1 pct, reverses Tuesday's loss
* Marks & Spencer jumps 8.2 pct after results
* Two-thirds of companies meet-beat forecasts -data
* Lack of new ECB measures could hit market rally -traders
By Blaise Robinson and Sudip Kar-Gupta
PARIS/LONDON, Nov 5 (Reuters) - European stocks rebounded on Wednesday, helped by positive company results which saw shares in British retailer Marks & Spencer surge more than 8 percent.
However, some traders said the stock market rally could be short-lived if European Central Bank (ECB) chief Mario Draghi fails on Thursday to unveil new economic stimulus measures to spur growth in the euro zone's struggling economy.
"If we get nothing from the ECB, which is a close call, we may see some downside," Philippe Gijsels, chief strategy officer at Fortis Bank, told Reuters Insider Television. (reut.rs/1vHB5Og)
Marks & Spencer jumped 8.2 percent after posting a rise in underlying first-half profit for the first time in four years, beating expectations, while German chemicals distributor Brenntag gained 4.5 percent, boosted by forecast-beating earnings.
Shares in Lundin Petroleum also advanced 2.6 percent after the Swedish oil and gas producer posted third-quarter earnings above expectations, while German reinsurer Hannover Re rose 1.4 percent after saying its net profit rose by a forecast-beating 21 percent.
Bucking the trend, however, was Finnish stainless steel maker Outokumpu which slumped 8.2 percent after reporting a bigger-than-expected quarterly loss.
About halfway into Europe's earnings season, 64 percent of companies have managed to meet or beat profit forecasts, while 59 percent have met or beaten revenue forecasts, according to Thomson Reuters StarMine data.
In absolute terms, profits are up 13 percent versus the same quarter a year ago, while revenues are down 0.2 percent, highlighting the fact that Europe's earnings rebound has mostly come from cost-cutting and lower financing costs.
The pan-European FTSEurofirst 300 blue-chip index was up by 1 percent at 1,340.34 points by the middle of the trading session.
The index had fallen 1 percent on Tuesday, extending losses in late trading after Reuters reported that central bankers in the euro area planned to challenge ECB chief Draghi over what they considered to be his secretive management style.
"The market is rising today, but without real conviction. There's no real trend on the market at the moment, and flows from investors remain thin," said Jean-Louis Cussac, head of Paris-based firm Perceval Finance.
Europe bourses in 2014: link.reuters.com/pap87v
Asset performance in 2014: link.reuters.com/gap87v
Today's European research round-up (Editing by Susan Fenton)