Ms Englaro is said to have opposed being kept alive artificially
A political standoff has developed in Italy over the right of a woman who has been in a coma for 17 years to die, despite a court ruling in her favour.
Italy's PM drafted an emergency decree to prevent feeding tubes being removed, but the president refused to sign it.
Doctors quoted by local media said they had begun withholding food on Friday and a lawyer said her family would continue moves to allow her to die.
Eluana Englaro, now 38, has been in a coma since a car crash in 1992.
The case has provoked fierce debate in the country.
Euthanasia is illegal in Italy and Prime Minister Silvio Berlusconi's position is supported by the Roman Catholic Church.
Last Sunday, Pope Benedict XVI added his voice to the debate about euthanasia, calling it a "false solution" to the tragedy of suffering.
Italy's President, Giorgio Napolitano, said Mr Berlusconi had acted unconstitutionally when he issued an emergency decree to prevent the woman's life-support machine from being disconnected.
He accused Mr Berlusconi of over-ruling a previous court decision to allow Ms Englaro to die.
Mr Berlusconi, who has a parliamentary majority, said an emergency session of parliament would enact a new law barring doctors halting nutrition to patients in a coma.
On Saturday he said he was "amazed that doctors who have vowed to save human lives can take part in the act that will surely lead to death, even cruelly by depriving the organism of food," AFP news agency reported.
On Tuesday Ms Englaro was transferred to a private geriatric clinic in the northern city of Udine, where doctors had agreed to disconnect her feeding tubes.
A lawyer for the Englaro family, Giuseppe Campeis, told Italian daily Corriere della Sera: "We are continuing with our (medical) procedure aimed at ensuring a 'gentle death'.
According to medical experts quoted by the paper, the process should become irreversible within three to five days.
Another report said it could take Ms Englaro about two weeks to die.
Last year Ms Englaro's father won a court battle allowing her to die. He said that before the accident, she had expressed a wish not be kept alive artificially.