* Berlusconi appealing against 4-year jail sentence
* Ex-PM in hospital with eye complaint
* Ally says court doctors are "Nazis" (Adds comments by Berlusconi ally, lawyer, doctors)
MILAN, March 9 (Reuters) - Court doctors ruled on Saturday that Silvio Berlusconi was able to attend a tax fraud appeal, rejecting the Italian ex-prime minister's complaint that an eye ailment prevented him leaving hospital and sparking furious protests from his allies.
The 76-year-old centre-right leader and media mogul faces a spate of trials this month as he fights for his political future following an inconclusive national election in February.
On Friday, a hearing in a trial where he is accused of having sex with an under-age prostitute was postponed after he entered hospital with an eye problem. The prosecutor complained that the hospitalisation was merely a delaying tactic.
On Saturday the Milan court handling the tax fraud case sent inspectors to examine him in the clinic where he was being treated by his private doctor, and ruled that his problem was not a "legitimate impediment" to him appearing in court.
"It's been rejected. We are carrying on," Piero Longo, one of Berlusconi's lawyers, told Reuters.
Berlusconi's doctor had said the inflammation in his patient's left eye caused him pain and disturbed vision. But the ruling meant the appeals hearing could go ahead on Saturday with or without the defendant being present.
Berlusconi is appealing against a four-year jail sentence for tax fraud in connection with the purchase of broadcasting rights by his television network Mediaset .
Berlusconi's political allies rallied to his defence with a chorus of attacks on the judges.
"A Stalinist court sent Nazi doctors to examine Berlusconi and issue a disgusting ruling," said Fabrizio Cicchitto, a top official in Berlusconi's People of Freedom party (PDL).
Niccolo Ghedini, another lawyer for Berlusconi, said it was "extremely grave" that the doctors had accepted that his client needed medical treatment but had still not put off the hearing.
"Of course it wasn't absolutely impossible for him for him to attend, that would need to be a life-threatening condition, but to have a hearing put off do you have to be on a stretcher surrounded by paramedics?" he said.
After the ruling, Berlusconi's doctor told reporters he had asked him to remain in hospital until Sunday.
Berlusconi denies all wrongdoing in the case and said on Thursday he was the victim of "judicial persecution ... which re-emerges every time there are politically complex moments in the political life of our country".
He fell short of victory in last month's election, even though he rallied his supporters and performed better than expected. The vote ended with a hung parliament and Italy's president is still struggling to form a new government.
The PDL has organised a public rally on March 23 to protest against prosecutors described by Berlusconi as the "cancer of our democracy".
Under Italian law, Berlusconi will not serve any jail time until the appeals process is exhausted.
In the tax fraud case, even if the appeals court upholds his previous 4-year jail sentence, it could still be overturned by a higher court. Two appeals are standard procedure in Italy's criminal justice system.
Berlusconi was convicted three times during the 1990s, before being either cleared by higher courts or benefiting from the statute of limitations by which cases expire if a final verdict is not reached within a given time period. (Reporting by Stephen Jewkes and Gavin Jones; Editing by Mark Heinrich)