Vivendi's Universal Music is not expected to offer concessions to EU antitrust regulators assessing its bid for EMI's recorded music unit, a person familiar with the matter said, a move that would trigger a lengthy investigation of the deal.

Universal is not likely to offer remedies in phase 1, but is likely to do so in phase 2, said the person, who declined to be identified because of the sensitivity of the matter.

Friday is the last day for Universal to offer concessions to European Commission regulators, who are scheduled to decide whether to clear the $1.9 billion deal by March 23.

An extended probe could take up to four months.

Companies in complex cases often prefer to delay offering concessions until the regulator conducts an in-depth probe, which can provide a clearer idea of regulatory concerns on which to base specific, possibly lighter remedies.

In an indication of the complexity of the case, the commission has assigned a team of 11 people, including three economists, to handle the brief.

The competition regulators have asked rivals and users whether the Universal deal, and a Sony-led <6758.T> plan to acquire EMI's music publishing business, will result in higher prices and also shut out competitors.

A questionnaire sent by the European Commission and seen by Reuters asked whether artists will be able to switch record labels easily and at a reasonable cost once the two deals are completed.

While the EU executive will decide by next Friday on the Universal-EMI deal, it has set an April 2 deadline for a decision on the Sony bid for EMI's music publishing operations.

Both Universal and the Sony-led group were expected to argue that strong competition in the music business, especially from online rivals such as Apple and Amazon , meant their acquisitions would not restrict the market.

Impala, a lobbying group for independent music companies, has called EU regulators to block both deals, saying they would reduce the number of competitors.

Rival Warner, which had also sought to buy EMI's recorded music, was expected to warn the Commission about the risks of an overly concentrated market.

(Reporting by Foo Yun Chee; editing by Rex Merrifield and Hans-Juergen Peters)