IMF chief Christine Lagarde on Monday warned of "consequences" if European countries try to renegotiate their debts, ahead of Greek elections which an anti-austerity party is tipped to win. "Collective endeavours are welcome but at the same time a debt is a debt and it is a contract," the International Monetary Fund's Lagarde told the Irish Times during a visit to Dublin. "Defaulting, restructuring, changing the terms has consequences on the signature and the confidence in the signature," she said.