The European Commission said on Monday it had opened an in-depth investigation into Cargill Inc's planned acquisition of Archer Daniels Midland Co's (ADM.N) chocolate business, citing concerns the deal could lead to higher prices.

The EU executive said it had until July 8 to investigate Cargill's planned $440 million acquisition, designed to expand the commodity trader's production capacity in North America.

The review could delay the closing of the deal, if it is ultimately approved. ADM previously said it expected the deal to close by July 1, but is "now targeting closing in mid-2015," spokeswoman Jackie Anderson said.

Cargill executives "still expect completion of the deal in mid-2015," spokesman Louis de Schorlemer said.

"The Commission needs to complete its process," he said.

The Commission said its preliminary investigation had shown potential competition concerns in the supply of industrial chocolate to customers in Germany and Britain, where Cargill, ADM and Barry Callebaut AG (BARN.S) were the main suppliers to customers.

"The proposed transaction could eliminate an important competitor and reduce the choice of suitable suppliers in already concentrated markets, which could lead to price increases," the Commission said in a statement.

Last year, ADM scrapped plans to sell its global cocoa and chocolate businesses after long-running negotiations collapsed. Cargill had been in final-stage talks to buy the combined operation, but sources told Reuters at the time that the reaction of regulators in Europe was a concern.

ADM later agreed to sell its chocolate business to Cargill and its cocoa business to Olam International Ltd (OLAM.SI) for $1.3 billion. ADM has said the deal with Olam is expected to close in the second quarter of 2015.

Regulatory reviews have previously caused trouble for ADM. In 2013, Australia rejected ADM's planned A$2.8 billion ($2.6 billion) takeover of grain handler GrainCorp Ltd (GNC.AX), saying it was not in the country's national interest.