Worries about a potential debt crisis in France boiled over last week, leading to a selloff in French bonds and a sharp rise in yields.

The spread between French and German bond yields expanded to its widest level since 2012. That difference in yields means investors are demanding much higher returns to hold debt from France compared with Germany, which is deemed a safer alternative.

The French bond rout has sparked fears of spillovers to other high-yield European debt markets, with some analysts drawing parallels with the eurozone debt crisis of the early 2010s.