The European Commission will follow EU antitrust chief Joaquin Almunia's advice to block the merger of Deutsche Boerse and NYSE Euronext next week, a person familiar with the matter said on Tuesday.

Almunia presented a 459-page document laying out his case to the other 26 commissioners last Friday, the person said. The college of commissioners will vote on the merger on February 1.

Twenty-five of the commissioners backed the EU competition commissioner. One wanted to read Almunia's recommendation in full, but is expected to go along with the others, the person said.

A second source, like the first speaking on condition of anonymity, also said that the merger would be blocked next week and that Michel Barnier, European Commissioner in charge of financial regulation, would not object to the halt.

Reached in Frankfurt on Tuesday evening, Deutsche Boerse Chief Executive Reto Francioni declined to comment. A spokesman for Deutsche Boerse added: We have not received formal notification from the European Commission.

Almunia on Tuesday reiterated the need for fair, efficient and competitive markets.

Preserving competition in this domain is of utmost importance and we will live up to our responsibilities in this regard, he told an industry conference in Paris.

Concerned about the combined entity's share of more than 90 percent of the listed derivatives market in Europe, Almunia had asked for Deutsche Boerse to sell its Eurex derivatives arm, or for NYSE Euronext to offload its London-based futures exchange Liffe.

The exchanges have refused. They can appeal against a negative decision at the EU courts in Luxembourg, but the process, likely to take between one and two years, could destroy the merger. The last time such appeals succeeded was in 2002.

Last week, national competition regulators in the European Union endorsed Almunia's proposed veto, a source with knowledge of the case told Reuters.

(Additional reporting by Edward Taylor in Frankfurt and Julien Toyer in Brussels; editing by Philip Blenkinsop, Barbara Lewis and Gerald E. McCormick)