Shares in Swiss pharmaceutical firm Lonza fell 2.7 percent after it said it was in advanced talks to buy U.S. drugs capsule maker Capsugel. Sources earlier told Reuters the deal could be worth more than $5 billion.

The STOXX Europe 600 was 0.07 percent lower, steadying after a rally last week brought the index to 11 month highs.

The STOXX Oil & Gas index <.SXEP> surged more than 2 percent after hitting its highest level since July 2015. Oil prices shot higher after OPEC and other producers reached their first deal since 2001 to jointly reduce output.

Italy's FTSE MIB <.FTMIB> rose 1.1 percent, outperforming the rest of Europe thanks to gains among its banks.

(Reporting by Danilo Masoni; editing by John Stonestreet)