London's leading share index has slid into the red in early trading, as eurozone contagion fears resurface following Cyprus' controversial bailout package.
Asian markets tumbled overnight and safe-haven bond yields fell following news EU member Cyprus is to impose an unprecedented bank levy on deposits held in the country.
The European Central Bank (ECB) could face extended losses as it prepares a last-ditch attempt to prevent a Greek exit from the eurozone.
Cyprus has told European authorities it intends to apply for a bailout, making the country the fifth eurozone country to request international aid.
Moody's has downgraded Spain's credit rating by three notches to Baa3 from A3, just above junk status, and placed it on review for further possible downgrades.