The European Union's incoming economy chief, Pierre Moscovici, vowed Thursday to be an impartial and tough enforcer of the bloc's deficit rules even though he failed to implement them as French finance minister.

France has missed several deadlines to bring its budget deficit under the EU limit of 3 percent of gross domestic product and to trim its debt burden.

Still, Moscovici, who was finance minister in France's center-left government until six months ago, vowed in a confirmation hearing in Brussels to be a "scrupulous guard of our rules" and not the "ambassador of one country."

"France must abide by the rules as all others," he insisted during an hours-long grilling by EU lawmakers.

Moscovici's nomination to the 28-nation bloc's executive Commission attracted sharp criticism from conservatives and deficit hawks, who said he cannot be trusted with enforcing rules he helped flout just months ago.

Conservative lawmaker Alain Lamassoure said nobody could "in good faith" trust Moscovici to enforce the EU rules, while fellow Christian Democratic Esther de Lange said Moscovici is poised to be a partial commissioner, acting like in George Orwell's novel Animal Farm "where some are more equal than others."

The new EU Commission, taking over in November, needs parliamentary approval, but lawmakers cannot veto specific commissioners.

The Commission gained important powers in the wake of the 18-nation eurozone's debt crisis to oversee national fiscal policies to prevent new imbalances that could jeopardize the bloc as a whole.

If countries are found to be violating the EU rules, the Commission can impose a tough monitoring system that undermines the nations' sovereign decision-making, plus it can impose economic sanctions as a last resort.

"These options are at our disposal," Moscovici said, insisting that he will be impartial in his enforcement decisions.

However, under a new working structure proposed by incoming Commission President Jean-Claude Juncker, Moscovici will be less powerful than his predecessors.

Moscovici's portfolio has been stripped of certain responsibilities that went to other commissioners and he will be answering to a Commission Vice-President, who will be able to veto his decisions, raising questions about how the new structure will work on a day-to-day basis.

"This is not about paternalism or oversight, this is about team work," Moscovici said in defense of the new system.