Nelson Mandela, former president of South Africa and champion of racial equality, has been hospitalized for an ongoing stomach problem.

The 93-year-old "has had a long-standing abdominal complaint and doctors feel it needs proper specialist medical attention," current president Jacob Zuma wrote in a statement issued Saturday.

Further details about Mandela's condition are unclear. The Nelson Mandela Foundation hasn't elaborated on the Nobel Peace prize winner's health.

Unnamed sources told BBC News that Mandela underwent surgery and is now in stable condition. He is reportedly expected to leave the hospital on Sunday.

Quoting a "family member," CNN is reporting that Mandela underwent a planned hernia surgery.

Mandela was hospitalized last year with an acute respiratory infection and released after a few days. During that time, a doctor acknowledged that Mandela took medication for a chronic, unnamed condition.

His recent hospitalization has renewed concern that the revered anti-apartheid icon's health is failing. Speculation over how serious Mandela's abdominal condition may be has flooded social networks.

In a message posted to Twitter, ITV News correspondent Rohit Kachroo said he's been told that Mandela's hospitalization is "really not an emergency."

The South African Military, which handled Mandela's health when he was hospitalized last year, has not issued a statement.

Mandela is revered as an influential force in the fight against racist apartheid rule in South Africa. Regarded by some as a martyr, he became president of the country in 1994 after spending 27 years in prison for championing the cause.

He once said he'd be prepared to die for "the ideal of a democratic and free society."

In his statement, Zuma gave Mandela his regards and requested that the public respect his privacy during this time.

"We wish him a speedy recovery and assure him of the love and good wishes of all South Africans and people throughout the world," he wrote.

Mandela has been increasingly absent from the public eye. He missed the African National Congress' 100th anniversary celebrations in January, reportedly because he was too frail to attend.

He did, however, meet with United States first lady Michelle Obama when she travelled to South Africa last year. He also attended the closing ceremony of the World Cup in July 2010.