SANTIAGO, Chile (Reuters) -- A Chilean appeals court ruled by a narrow margin on Wednesday that former dictator Augusto Pinochet can face charges related to the 1975 cover-up of the killings of dozens of leftists, known as Operation Colombo.

Judge Juan Escobar, president of the Santiago Appeals Court, told reporters that the court voted 11-10 to remove Pinochet's immunity from prosecution in the human rights case.

The defense for Pinochet, 89, is expected to appeal the ruling to the Supreme Court. Pinochet ruled Chile from 1973 to 1990, a period when more than 3,000 people died in political violence.

Judge Victor Montiglio, who is investigating and prosecuting the Operation Colombo case, wants to charge Pinochet with responsibility in covering up the murders of up to 119 political opponents including armed rebels from the Revolutionary Leftist Movement.

The cover-up involved planting news stories in Argentina and Brazil alleging that the guerrillas had died fighting among themselves.

Human rights lawyers say they were taken prisoner by Chile's secret police and killed.

"It was close, but we are happy with the decision to accept the prosecution's motion to remove immunity. If it is appealed, the Supreme Court should definitely uphold this ruling," said Hernan Quezada, a human rights attorney who represents families of the victims.

Chile has been ruled by a center-left coalition for 15 years, but up until recently public opinion on Pinochet was deeply divided. While many revile him, others admire what they say was his role in saving Chile from communism.

But even ardent supporters have turned against Pinochet in the last year, when a government commission established that more than 20,000 people were tortured in the Pinochet era, and it came out that he hid millions of dollars from tax authorities in secret off-shore accounts.

Pinochet is accused of dozens of human rights abuses and has been formally charged in a few cases. Courts must decide on a case-by-case basis whether to remove his immunity, a privilege of former presidents.

No case has come to a conclusion because Pinochet's defense has successfully argued he is too frail to defend himself. He has a heart condition, diabetes and mild dementia caused by frequent mini-strokes.

"We have sustained that he cannot be criminally charged since he can't even interact in court due to his bad health. What I'm saying is he can't even answer questions," said defense attorney Pablo Rodriguez.

"None of these allegations are based in fact. This is a media show and part of what has become a traditional persecution of General Pinochet and the regime he headed," he added.