Several environmental groups have asked a federal appeals court to disqualify a judge from a lawsuit over the Obama administration's initial six-month moratorium on deep-water oil drilling.

U.S. District Judge Martin Feldman overturned the temporary drilling ban in June and refused last month to withdraw from the case.

In a court filing Thursday, environmental groups supporting the moratorium asked the 5th U.S. Circuit Court of Appeals to remove Feldman from the case because of his investments in several oil and gas companies. Feldman says he learned he owned Exxon Mobil stock a day before he ruled and sold it several hours before he issued the decision.

Last month, a 5th Circuit panel rejected the government's bid to restore its six-month ban on issuing new permits for deep-water drilling and suspension of 33 existing drilling projects in the Gulf of Mexico.