LOS ANGELES (REUTERS) - Led Zeppelin singer Robert Plant and guitarist Jimmy Page appeared in a Los Angeles court for a civil trial that opens on Tuesday in which they are accused of stealing the opening chords of their 1971 classic Stairway To Heaven from another band.

Plant, 67, and Page, 72, did not speak to each other or their lawyers as they appeared in federal court. Both sported long grey hair and Page wore a three-piece suit.

The lawsuit alleges that the opening chords of their song were stolen from the 1967 instrumental Taurus by the band Spirit.

US District Judge Gary Klausner in Los Angeles said in April that a jury might find "substantial" similarity between the first two minutes of Stairway and Taurus, and to let it decide whether Plant and Page were liable for copyright infringement.

Trial in the case is set to begin later on Tuesday with jury selection, followed by opening arguments.

The lawsuit was brought by Michael Skidmore, a trustee for the late Randy Wolfe, also known as Randy California, Spirit's guitarist and the composer of Taurus.

Skidmore said Page may have been inspired to write Stairway for Led Zeppelin after hearing Spirit perform Taurus while the bands toured together in 1968 and 1969, but that Wolfe never received credit.

Stairway To Heaven is considered one of the most widely heard compositions in rock history and is the signature song of Led Zeppelin.

Earlier on Tuesday, Klausner ruled on a string of motions including one that would limit the testimony of Spirit bassist Larry Knight to just his observations of interactions between Page and Wolfe.

Knight would not be allowed to give direct quotes or discuss exactly what was said between Page and Wolfe.

Larry Iser, an attorney who has represented the Beatles and Michael Jackson and is not directly involved in the case, said in a phone interview the opening riff in dispute, which features a minor key and a descending base line, is a common musical device.

It has been used on the Beatles' While My Guitar Gently Weeps and Led Zeppelin's own recording Babe I'm Gonna Leave You, Iser said.

Attorneys for Led Zeppelin have argued the chord progressions cited in the civil lawsuit were so cliched that they did not deserve copyright protection.