* FTSEurofirst 300 down 1.1 pct, Euro STOXX 50 down 1.65 pct
* Glencore set for worst daily drop on debt worries
* VW shares fall to 4-yr low as emissions scandal rumbles on
* Vodafone down after ending talks with Liberty Global
* Banks help Spain's IBEX outperform after Catalan vote
By Sudip Kar-Gupta and Danilo Masoni
LONDON, Sept 28 (Reuters) - European shares fell on Monday, with miner Glencore seeing nearly a quarter of its value wiped out by debt concerns and carmaker Volkswagen , which has been hit by an emissions data scandal, extending losses.
The pan-European FTSEurofirst 300 index was down 1.1 percent, while the euro zone's blue-chip Euro STOXX 50 index fell 1.65 percent, with both markets retreating after rising by around 3 percent on Friday.
European stock markets have steadily lost ground from peaks reached in April, partly due to concerns about an economic slowdown in China.
"Overall sentiment remains negative for now while there is much talk about a squeeze on earnings and lower economic growth in the months ahead," said Peregrine & Black senior sales trader Markus Huber.
Over the weekend International Monetary Fund head Christine Lagarde said the IMF was likely to revise downwards its estimates for global economic growth due to slower expansions in emerging economies.
Glencore fell 21 percent after a bearish Investec note questioning the mining group's value given its high level of debt and the continued slump in metal prices. The stock was set for its worst one-day drop ever.
Volkswagen shares were among the worst performers in Europe, falling 5.7 percent to their lowest levels in 4 years after two German newspapers reported on Sunday that the carmaker's own staff and one of its suppliers warned years ago about software designed to thwart emissions tests.
VW shares have fallen by more than 30 percent over the last week after the company acknowledged installing software in diesel engines designed to hide their emissions of toxic gasses.
Spain's benchmark IBEX index outperformed with a 0.55 percent decline, after Catalan secessionist won a majority of seats in a regional vote but were not seen to have a clear mandate to push for independence.
Spanish banks outperformed their European peers, led by gains in Sabadell and Bankinter, helped by plans by Spain to change tax rules for Deferred Tax Assets (DTAs), a move the government said would strengthens their solvency.
Vodafone fell 3.9 percent after the mobile phone group said it had ended talks with Liberty Global about exchanging assets to better compete in Europe's converging telecoms and media markets.
However, there were signs elsewhere that merger activity remained alive, with SAB Miller shares rising 2.7 percent after the Sunday Times newspaper reported that Anheuser-Busch InBev SA could bid about $106 billion for SABMiller within days.
Today's European research round-up (Editing by Toby Chopra)