A US reporter has said she is reluctant to divulge a confidential source to prosecutors investigating the leaking of an undercover CIA agent's identity.
Ms Miller says she finds the ruling "frankly frightening"
New York Times reporter Judith Miller faces jail for refusing to testify.
Ms Miller, who gathered material for a story but never wrote one, was held in contempt by a judge in Washington.
But she told NBC television she would have to be sure the source's decision to be identified was voluntary before she would consider a disclosure.
"Supposing the investigation is beyond this one source to
other sources, whom I may not be able to ask how they
feel?" she said.
here is whether or not I'm going to protect them and our
readers by being able to do my job," she added.
US District Judge Thomas Hogan has said Ms Miller can
remain free while pursuing an appeal against Thursday's ruling.
"It's frankly frightening that just for doing my job and talking
to government employees about public issues, I may be deprived of my
freedom and family," Ms Miller said in a statement.
CIA agent Valerie Plame's husband says her name was leaked in retribution for an article he wrote challenging the US government over the war in Iraq.
Investigators are probing whether the leak was illegal, and claims that government officials were involved.
Several leading government officials have already testified to the grand jury or been interviewed by prosecutors - among them Secretary of State Colin Powell, National Security Adviser Condoleezza Rice and former CIA Director George Tenet.
The jury is probing any link between the leak and the White House
President George W Bush himself was interviewed in June at the White House.
Ms Plame's husband, former US charge d'affaires in Baghdad, Joseph Wilson, had been sent by the CIA to Niger to investigate claims that then Iraqi leader Saddam Hussein had tried to obtain uranium for nuclear weapons.
He concluded there was no evidence of this, but Mr Bush still referred to the claims in his State of the Union address.
A week after Mr Wilson's article appeared questioning the Niger allegations, Ms Plame was exposed by journalist Robert Novak, who said he based his report on the comments of two unidentified senior administration officials.
A report in the Washington Post newspaper later suggested that White House officials blew the cover of Mr Wilson's wife in order to discredit him, by suggesting he had been given the Niger mission only at her urging.
Disclosing a covert agent's name is a criminal offence in the US, punishable by up to 10 years in prison.