BRUSSELS (Bloomberg) - European Union (EU) regulators charged Gaz de France SA and E.ON AG, Germany's biggest utility, with breaking EU anti-trust rules by agreeing not to sell natural gas in each other's markets.

The European Commission said in a statement yesterday that it sent the claims, known as statements of objections, to the companies.

Gaz de France, the operator of Europe's largest natural-gas grid, said in a statement that it received a letter from the Brussels-based commission voicing "suspicions of collusion" with E.ON on pipeline deliveries of natural gas.

The EU has increased its scrutiny of companies in the bloc's 340 billion-euro ($525 billion) power and gas market. The EU is considering legislation that would require gas producers to sell their transmission networks, spin off that business or hand over operation of the grid to an independent company.

E.ON spokesman Christian Drepper said the Dusseldorf-based company is "confident" that it will dispel the EU's concerns.