Perus ex-president Alberto Fujimori, who is in prison for human rights abuses and corruption, has been hospitalized for pancreas problems, his doctor said Monday.

It is the latest in a series of health crises for the 78-year-old former leader.

"The ex-president has been suffering from pancreatic problems. He is having digestive pain. Upon evaluation, it was advised that since there was no improvement, the best option would be to hospitalize him," doctor Alejandro Aguinaga told the N news channel.

Fujimori was hospitalized Sunday with a cyst on his pancreas, and will undergo a high-resolution magnetic resonance imaging exam (MRI), Aguinaga said.

The latest hospitalization -- the ex-president's second this month -- comes against a backdrop of friction between President Pedro Pablo Kuczynski and the opposition, which is led by Fujimori's daughter Keiko.

The former president's health has become a hot-button issue as Kuczynski fends off attacks from the Fujimori camp, which holds a majority in Congress.

Kuczynski has rejected calls to pardon the ex-president.

But he has said that if Congress passes a bill granting Fujimori house arrest, he will sign it.

He was convicted in 2009 for his role in killings by a death squad targeting supposed guerrillas in the 1990s.

He has also been convicted of embezzlement and bribery. His sentence, which totals 25 years, began in 2007.