The U.S. Internal Revenue Service has asked a judge to let it to continue to seek unpaid back taxes from Allen Stanford, the billionaire Texan accused of an $8 billion fraud by U.S. regulators, court documents show.

Stanford and his wife Susan owe the U.S. government $226.6 million in unpaid federal income taxes between 1999 and 2003, the IRS said in a filing with a federal court in Dallas on March 13.

Stanford's tax debt could inflate even more as he hasn't filed his income tax return for 2007, the IRS said.

Regulators have accused Stanford of running a massive Ponzi scheme.

Earlier this month, the court-appointed receiver in charge of the operations and assets of Stanford's businesses told 1,000 Stanford employees their jobs have been terminated, and a federal judge granted the U.S. government's request to indefinitely freeze the assets of Stanford.

(Reporting by S. John Tilak in Bangalore; Editing by Hans Peters)