The boss of the European Central Bank has raised expectations that it might step in to help lower excessive borrowing costs that are putting pressure on eurozone government finances.
Speaking in London, Mario Draghi said that the bank would "do whatever it takes to preserve the euro" and added: "Believe me, it will be enough."
The FTSE 100 closed 1.36% up while Spain's battered Ibex recorded a 6.06% boost.
The encouraging signs come after a week of poor market closes, with Spain's bond yields reaching record highs above an unsustainable 7.5% recently.
On Thursday afternoon, the 10-year Spanish yield rate also dropped below the psychologically important 7%.
US stock futures jumped sharply after the comments from Mr Draghi to preserve the eurozone at all costs.
However, some sources within the ECB have downplayed Mr Draghi's assertions and told Sky's Economic Editor Ed Conway the comments are "nothing new".
Meanwhile, Moody's raised the alarm on Slovenia's three largest banks, downgrading them by several notches and saying they were the weakest capitalised lenders in central and eastern Europe.
The credit rating agency said that the downgrades reflected the deterioration of the banks' financial fundamentals.