dallas (Bloomberg) — A US judge extended a freeze on some investor accounts as investigators probe an alleged $8 billion fraud at companies controlled by Texas financier Allen Stanford.

Hundreds of investors in Stanford Group Co. asked US District Judge David Godbey in Dallas to unlock funds frozen last month, when regulators accused Stanford and his companies of devising a massive Ponzi scheme. Godbey yesterday granted the US Securities and Exchange Commission's request for a restraining order that would apply to about 16,000 accounts, or half the total, valued by receiver Ralph Janvey at more than $1 billion.

The SEC sued Stanford, two associates and three affiliated companies on February 17, claiming they orchestrated an $8 billion fraud through the sale of high-yield certificates of deposit through Antigua-based Stanford International Bank. Godbey froze all of Stanford's corporate and personal assets and appointed Janvey, a Dallas lawyer, as receiver for the companies.

Janvey is asking Godbey to release accounts that aren't linked to the suspected CDs or certain Stanford executives or employees. That would allow investors to access roughly 16,000 accounts worth about $4.1 billion, Janvey said in court papers filed yesterday.

About 12,000 Stanford customers began retrieving an estimated $500 million in frozen funds on March 9, when Godbey ordered Janvey to release accounts valued at less than $250,000 that weren't tied to the suspected fraud.

Godbey originally set the freeze on all accounts to expire tonight. He ordered Janvey to submit a plan addressing investor concerns regarding the remaining frozen accounts by March 16.

Janvey's request "falls far short of what the receiver says he is trying to accomplish", attorney Michael Quilling said in a motion filed March 9 on behalf of investors whose accounts remain frozen. "The litmus test is not size. Size is meaningless. The only true litmus test is 'tainted' versus 'not tainted'."

Janvey and the SEC were sued on March 4 by more than 30 former Stanford financial advisers and clients who claim their rights under the US Constitution were violated when their assets were seized even though they hadn't been accused of wrongdoing.

In addition to the SEC, the Federal Bureau of Investigation, Internal Revenue Service and US Postal Service are investigating Stanford Financial Group companies and officials.

Neither chairman Allen Stanford nor chief financial officer James Davis has been charged with a crime. Chief Investment Officer Laura Pendergest-Holt, who also was sued by the SEC, was charged with criminal obstruction and released on $300,000 bond. Her lawyer, Dan Cogdell, said she is innocent and was cooperating with investigators when she was arrested February 25.