WASHINGTON, June 25 (Reuters) - The U.S. Supreme Court on Monday let stand a ruling that a large Christian cross as part of a war memorial in California violated the constitutional ban on government endorsement of religion.

The justices rejected an appeal by the Obama administration and by an association that erected the cross arguing the government should not be forced to take down the memorial cross that stood atop Mount Soledad in San Diego since 1954 to honor veterans.

The case involved whether a religious symbol can be prominently displayed on public land and whether the cross violated the U.S. Constitution's requirement on church-state separation.

The Supreme Court has been closely divided and has struggled for years to come up with clear rules on what religious displays, ranging from crosses to the Ten Commandments, can be put on public property, along with secular items.

The Supreme Court ruled in 2010 that a federal judge erred by ordering the removal of a large Christian cross as part of a war memorial in a remote part of the California desert. But that ruling did not decide the constitutionality of the cross.

The 43-foot high San Diego cross is surrounded by walls displaying granite plaques that commemorate veterans or veterans groups. Located between the Pacific Ocean and an interstate highway, it can be seen for miles.

Easter services were held annually at the cross from 1954 until at least 2000, according to court documents.

The cross has been the subject of litigation since 1989 when two veterans sued San Diego in an effort to get it off city land. In 2006, Congress intervened in the dispute, resulting in the federal government taking ownership of the property.

A group of plaintiffs, including the Jewish War Veterans of the United States of America, then sued. A U.S. appeals court ruled for the plaintiffs that the dominance of the cross in the memorial conveyed a message of government endorsement of religion.

The Obama administration and a group called the Mount Soledad Memorial Association, which erected the cross, supported by 20 states and various veterans groups, appealed to the Supreme Court in arguing the cross should be allowed as part of the memorial.

Solicitor General Donald Verrilli said in the administration's appeal that the government would have to "tear down" the cross if the Supreme Court rejected its petition.

A. Stephen Hut, an attorney for the plaintiffs, opposed the administration's appeal. He wrote in a brief filed with the high court that the appeals court correctly concluded, based on the history, location and visibility of the cross, that its continued display violated the First Amendment.

The Supreme Court stayed out of the dispute, issuing a brief order that denied the appeals by the administration and the association without comment.

Justice Samuel Alito issued a separate statement saying the denial of the appeals does not amount to a ruling on the merits.

Alito wrote that the federal government can raise the same issue later after an entry of final judgment in the case. He said it remained unclear precisely what action the federal government will be required to take.

The Supreme Court cases are Mount Soledad Memorial Association v. Trunk, No. 11-998, and United States v. Trunk, No. 11-1115.

For Mount Seledad Memorial Association: Allyson Ho of Morgan, Lewis & Bockius.

For the United States: Donald Verrilli Jr., Solicitor General of the United States.

For Trunk: Stephen Hut Jr. 

(Reporting By James Vicini)

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