Greece must respect the euro zone's rules and cannot demand special treatment for its debt in the wake of the victory of anti-austerity party Syriza, International Monetary Fund chief Christine Lagarde said in a newspaper interview on Monday.

"There are internal euro zone rules to be respected," Lagarde told Le Monde daily. "We cannot make special categories for such or such country."

Lagarde added that Greece still needed to carry out key reforms, such as tax collection and reducing judicial backlogs.

"It's not a question of austerity measures, these are in-depth reforms that remain to be done," she said.