The European Union's executive commission is to decide next week whether to open a formal investigation into the Italian banking sector over competition concerns, spokesman Oliver Drewes said Wednesday.

The commission is currently "making a preliminary assessement" about whether certain Italian banks that enjoy cooperative status should in fact have this revoked, he said.

Should the assessment confirm this view, it would impact on shareholder voting rights in the sector. Cooperative banks are run on the basis of one shareholder per vote rather than the standard one-share-per-vote structure.

"We are also looking at who is listed (on the stock exchange) as (such banks) should be acting under normal banking rules," Drewes said.

A dispute has been simmering between Italy and the commission, which has the job of policing competition issues in the EU, over whether the country's banking system operates protectionist policies.

The conflict has threatened to come to a head since Dutch bank ABN Amro and Spanish bank Banco Bilbao Vizcaya Argentaria recently launched respective takeover bids for cooperative bank Banca Antonveneta and Banca Nazionale del Lavoro.