Virginia's federal public defender objected Wednesday to an attempt by government lawyers to block him from representing an American-born prisoner captured in Afghanistan.

In a telephone interview from his Alexandria office, public defender Frank Dunham Jr. said the government's argument that taxpayers should not pay for Yaser Esam Hamdi's defense when his father is a successful oil engineer in Saudia Arabia "borders on the frivolous."

"It's not the father, it's the son whose assets are to be considered," Dunham said, summarizing the response his office filed to the government's argument.

Government lawyers filed court papers Tuesday asking a federal judge to terminate his appointment of Dunham or require Hamdi's father to demonstrate financial eligibility for court-appointed counsel.

A copy of the public defender's response filed Wednesday was not available from the courthouse. The clerk's office said the documents were in the judge's chambers and not available for public viewing.

U.S. District Judge Robert Doumar appointed the public defender based on an affidavit by Esam Fouad Hamdi that his son has no assets to retain a lawyer and that he would be unable to pay for legal services for his son.

The government argued that since Yaser Hamdi didn't seek an attorney for himself, his assets are irrelevant.

Doumar has ordered the government to explain in writing by Thursday why it is holding Hamdi, who was captured in November after a prison uprising by Taliban and Al Qaeda members.

The 21-year-old Hamdi was held at Guantanamo Bay, Cuba, until it was discovered he was born in Louisiana to Saudi Arabian parents. He was moved to the jail at the Norfolk Naval Base in April.

Dunham has been trying since May to provide Hamdi with legal representation and seek his release. The government has argued it considers Hamdi an enemy combatant who can be held indefinitely without being charged or allowed to see a lawyer.

Doumar previously ordered the government to allow Dunham to meet with Hamdi, but his order was overturned by the 4th U.S. Circuit Court of Appeals in Richmond.