BRUSSELS (Reuters) -- Former French prime minister Edith Cresson should be deprived of half her pension relating to her controversial term as a European commissioner, an adviser to Europe's top court said on Thursday.

"In the opinion of (the) advocate general ... Cresson is correctly accused of favoritism by the Commission, in breach of her obligations as a commissioner," the European Court of Justice said in a statement.

"He proposes that such actions merit a pecuniary sanction and therefore suggests that the Court deprive Cresson of 50 percent of her pension rights," the statement said.

The European Commission has accused Cresson of breaching her treaty obligations by hiring a dentist and personal friend from her French constituency as a scientific adviser.

The case in the ECJ was launched in 2004.

The non-binding opinions of the advocates-general are followed by the court in more than half the cases.

Cresson was commissioner for education, research and training when she became the center of allegations of nepotism and mismanagement that led to the mass resignation of the Commission headed by Jacques Santer of Luxembourg in 1999.

A Belgian court dismissed criminal charges against her in 2004 and her lawyers demanded that the Commission should drop its administrative proceedings against her.