HOUSTON, April 7 (Reuters) - A federal appeals court rejected a request from a group of Stanford Group Co investors on Tuesday to lift an order freezing $1.7 billion in assets.

Investors who have funds controlled by a court-appointed attorney asked the U.S. Court of Appeals for the Fifth Circuit in New Orleans on Monday to stay a lower court's order that freezes their assets for an indefinite period.

But the appeals court denied the request in a two-sentence order that did not provide a reason for its decision.

Texas billionaire Allen Stanford, two of his top aides and three of his companies face civil charges from the U.S. Securities and Exchange Commission. They are accused of an $8 billion fraud involving high-yield certificates of deposit.

Ralph Janvey, an attorney appointed by a federal judge in Dallas to oversee the Stanford's operations, has frozen many accounts he believes are linked to the fraud in a bid to preserve assets for investors.

Michael Quilling, an attorney for the investors, could not be reached immediately for comment.

Janvey has released 28,000 accounts, or 80 percent of the Stanford accounts, and allowing investors to intervene in the case would be disruptive, he said in court papers.

Stanford's civil case can be found in U.S. District Court in Dallas, case number 3:09-cv-298. The investors' motion, filed in New Orleans, is case number 09-10325. (Reporting by Anna Driver; editing by Leslie Gevirtz)