Former Panamanian dictator, CIA spy and convicted cocaine trafficker Manuel Noriega was in a coma on Tuesday after suffering a hemorrhage from an operation to remove a benign brain tumor, representatives for the 83-year-old said.

"He has a major brain hemorrhage and is in serious condition," his daughter Lorena Noriega told reporters outside the hospital in Santo Tomas where he was operated on, describing his state as "critical."

He underwent a second operation that stopped the bleeding, said his lawyer, Ezra Angel, adding that his client was in an induced coma.

Noriega ruled Panama from 1983 to 1989, spying for the Central Intelligence Agency before the United States invaded in 1989, toppling his brutal regime and ending a drug-trafficking career that associated him with Colombian kingpin Pablo Escobar.

Angel said the second operation in eight hours had been carried out with "open skull" and that Noriega's high blood pressure may have contributed to the hemorrhage.

Noriega was initially sentenced in the United States in 1992 and is currently serving time for murder in Panama. Judicial authorities had granted Noriega a period of house arrest until April 28 to undergo the operation.

As military ruler, Noriega made headlines as his relationship with Washington soured, prompting the United States to send in nearly 28,000 troops to seize Panama City and capture him in a house-to-house hunt.

Noriega orchestrated the disappearance of scores of opponents, some of whose bodies later turned up in exhumations at the former Tocumen military base, bound and showing signs of torture.

"I hope that one day the country will know the truth about Gen. Noriega, and the families who lost their loved ones can be free, close this chapter and move on," Panamanian President Juan Carlos Varela said on Tuesday.