The leader of the far-right Alternative for Germany (AfD), the second largest party in parliament after Sunday's election, said Germany's likely next chancellor would be held hostage by left-wing parties that would seek to loosen tough fiscal rules.

The far-right Alternative for Germany (AfD) and Germany's Left party between them garnered the one third of seats in parliament needed to block changes to the constitution, including a loosening of the debt brake which restricts deficits to 0.

Germany's mainstream conservatives have won the country's national election, while a far-right party surged to become the country's second-largest party.