BRUSSELS (Reuters) -EU antitrust regulators have resumed their investigation into candy maker Mars' $36 billion bid for Pringles maker Kellanova, setting a December 19 deadline for their decision, according to an update on the European Commission website.

The Commission, which acts as the EU competition enforcer, temporarily halted its probe in late July while waiting for the companies to provide requested information.

It opened a full-scale investigation in June, warning that the deal could lead to price hikes and may boost Mars' negotiating power with retailers.

The deal, among the biggest in the sector and already cleared unconditionally in the United States, would bring brands from M&Ms, Snickers and Whiskas to Pringles, Pop-Tarts and Kellogg cereals under one roof.