Issa: Justice protecting its political appointees

US Attorney General Eric Holder is facing a contempt vote before a Congressional committee over a botched US sting operation.

President Barack Obama used executive privilege to withhold documents that the justice department says would harm ongoing criminal investigations.

Republican committee chairman Darrell Issa says the documents are necessary for the committee to finish their investigation and the justice department has not been co-operative.

"Over and over again the department has sought to protect its political appointees," Mr Issa charged during Wednesday's hearing.