The European Commission is expected to finally approve Italian energy giant Eni SpA's (E) sale of stakes in three natural gas pipelines by the end of September, a person familiar with the situation said Thursday.

Eni last February offered to sell its stakes in three international natural gas pipelines to end a European investigation into market abuse and avoid a potential fine of more than EUR1 billion.

Eni values the stakes at a total of around EUR1.5 billion.

The company had allegedly blocked competition on the Italian gas market by hoarding capacity in its international pipeline network and deliberately underspent on upgrades so keeping capacity low, despite strong demand by other gas distributors.

The commission--the European Union's antitrust body--has market-tested the company decision, asking other operators and competitors if the measure would be effective. After a positive result from such a test, the final decision will likely be made official with a publication on the EU official journal by the end of September, the person told Dow Jones Newswires.

The company is offering to sell stakes in the TAG pipeline, which carries Russian gas to
Italy through Austria , and in the TENP and Transitgas pipelines, which cross Germany and Switzerland .