By Vanessa Mock

BRUSSELS--European Union competition chief Joaquin Almunia has described negotiations over Universal Music Group's proposed acquisition of EMI Music as "very tough."

Speaking during an interview in Brussels late Tuesday, he said discussions with UMG were continuing but gave no indication on when the music giant would come with its offer to address major regulatory concern over the $1.9 billion deal. The tie-up would create a music behemoth in Europe and give the merged entity a market share of over 50% in some key European countries.

In recent days, the European Commission team that is reviewing the deal has questioned the company's plan to reduce its market share below 40%, further delaying progress in the negotiations, according to people familiar with the matter.

"It's true that it's very tough," Mr. Almunia said, referring to efforts to find a breakthrough on weeks of talks. "There will be a lot of work looking at this merger."

During a press conference Wednesday, Mr. Almunia confirmed that regulators were still waiting for a package of so-called remedies from Universal. "Once we receive them...we will market test those remedies and assess the results during August."

The final deadline for regulators to give their decision is the end of September.

Universal is due to pay EMI Music's owner, Citigroup Inc. (C), more than $1.7 billion of the purchase price by early September, regardless of whether regulators have approved the deal by then. Citi and Universal, which is owned by Vivendi SA (VIV.FR), have discussed extending the payment deadline by about two months, but haven't reached an agreement.

Write to Vanessa Mock at vanessa.mock@dowjones.com

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