* Hearing set for June 21
* Warner Music, others oppose transaction
WASHINGTON, June 14 (Reuters) - The chief executives of Universal Music Group and EMI Group are slated to appear next week before a congressional panel to defend plans for Universal to buy a big piece of rival EMI.
Combining Universal Music Group, which has a star lineup of Lady Gaga and Rihanna, with EMI's recorded music unit, whose catalog includes the Beatles and Katy Perry, would give the industry leader a 40 percent market share.
Some argue it would lead to higher prices for both digital music and CDs.
Universal Chairman Lucian Grainge and EMI Group Chief Executive Officer Roger Faxon will appear before the antitrust subcommittee of the Senate Judiciary Committee on June 21, the committee said.
A third witness, Irving Azoff, chairman of Live Nation Entertainment, Inc, is also expected to support the bid by Universal, owned by Paris-based Vivendi, to buy EMI's recorded music unit from Citigroup. The proposed transaction, which was announced in November, is worth $1.9 billion.
Three critics of the deal are set to appear. They are: Warner Director Edgar Bronfman, Jr, Beggars Group Chairman Martin Mills and Gigi Sohn, president of the public advocacy group Public Knowledge.
The Federal Trade Commission, which is reviewing the deal to ensure it complies with antitrust law, has asked industry experts about Universal's power to set prices given widespread music pirating and big retailers like Apple and Amazon , who use cheap music to attract customers.
It is also asking about allegations made by consumer groups and others that Universal has been reluctant to license its enormous catalog of must-have music to digital startups, or has licensed the music only on onerous terms.
Universal has defended the deal as good for consumers because it would allow the company to increase investment in digital services.
In Europe, where the deal also faces an antitrust review, the European Commission is preparing a formal "statement of objections."
Universal has said it would work with the Commission to get the deal approved, most likely by selling some assets.
Separately, the European Commission gave its approval in April to a consortium led by Sony to buy EMI's music publishing business.