The spike in Portuguese borrowing costs following the teetering of the governing coalition of Pedro Passos Coelho on Tuesday could force EU and International Monetary Fund officials into a discussion they had thought they could put off for several months: will Lisbon need a second bailout?

Thanks to the eurozone-wide rally in bonds over the past year, Lisbon was able to get over the biggest immediate hurdle that could have forced it to seek more bailout aid: a €10bn bond that had to be repaid at the end of September.

Late last year, Lisbon was able to swap €3.8bn due for longer-dated bonds, and earlier this year it was able to go to market to raise almost all the rest: in January, it was able to borrow €2.5bn at below 5 per cent in an auction of five-year bonds, and the sale of 10-year debt in May raised another €3bn at 5.7 per cent.