* STOXX 600 up 0.5 pct to new three-month high
* Spain's IBEX loses 1.2 pct
* Spanish banks drop on Catalan jitters
* SocGen "buy" boosts Ubi Banca
* Airlines jump after Monarch goes bust (Adds closing prices, quotes)
LONDON, Oct 2 (Reuters) - Spanish stocks sank on Monday after violence surrounding Catalonia's independence referendum fuelled political worries and left Madrid's bourse missing out as European shares hit a three-months high and Wall Street fresh new records.
The pan-European STOXX 600 began the fourth quarter with a 0.5 percent gain, boosted by a weaker euro. But Spain's IBEX fell 1.5 percent after Catalans defied a police crackdown to vote for independence in a referendum the Spanish government said was unconstitutional.
Spain's IBEX has been a strong performer among European benchmarks, up 10 percent in the year to date, but lost some of its shine leading into the referendum.
Shares in Catalonia-headquartered Banco Sabadell and Caixabank were the worst-performing within the Spanish index, down 4.4 and 4.5 percent each.
Euro zone lenders felt some of their Spanish counterparts' pain, and lost 0.7 percent.
"There is clearly a Catalan effect" for financial shares, said Stephane Barbier de la Serre, a strategist at Makor Capital Markets.
In the longer run, the Catalonian crisis is unlikely to derail the bullish trend of the sector, he said, explaining tighter monetary policies would gradually push rates higher, benefiting lenders.
Not all banks fell. Italy's UBI Banca jumped 4.6 percent to the top of the FTSE MIB after Societe Generale upgraded the stock to a "buy", saying higher Italian GDP forecasts indicated growing lending demand and better non-performing loan management.
Outside financial stocks, European markets seemed immune to the events in Spain.
EasyJet, Ryanair and Lufthansa were among top gainers, up between 3.5 and 5.2 percent after Monarch Airlines went bust.
Travel and leisure stocks gained 0.9 percent as airlines rose on the prospect of carving up Monarch's assets, in the sector's latest failure after Alitalia and Air Berlin succumbed earlier this year.
"Capacity being taken out of the market was always going to be good news for other airline stocks ... but the collapse of Monarch does highlight serious issues for the airline industry," said Rebecca O'Keefe, head of investment at Interactive Investor.
Ballpoint pen and razor maker BIC posted the worst performance and fell 9.9 percent after lowering its 2017 sales forecast because of weaker-than-expected performance in U.S. and Latin American markets.
(Reporting by Helen Reid and Julien Ponthus; Editing by Larry King)