Europe's main stock markets tumbled at the open Tuesday as the Russia-Ukraine crisis escalated, triggering planned Western sanctions against Moscow.

London's benchmark FTSE 100 index shed 1.2 percent to 7,394.82 points. In the eurozone, Frankfurt's DAX fell two percent to 14,435.37 points and the Paris CAC 40 retreated 1.8 percent to 6,665.06.