Singapore's Foreign Ministry said in a statement that the wife of former President Susilo Bambang Yudhoyono died at National University Hospital, where she had been treated since February.

"She has left us forever in peace and the family has sincerely let her go," Hatta Radjasa, a representative of the family, told reporters in the hospital. He said that Yudhoyono had been at his wife's bedside throughout her treatment.

Radjasa, the father-in-law of Yudhoyono's second son, said Indonesia's government had ordered a state funeral at Jakarta's Kalibata heroes cemetery for the former first lady, whose body is expected to be returned to Jakarta on Sunday morning.

Indonesian President Joko Widodo expressed condolences at a news conference at the presidential palace in Bogor, Indonesia.

"I call on Indonesians to pray together for her, may she have the best place by God and may the family that left behind have patience," Widodo said.

Kristiani Herrawati Yudhoyono, a politician who was known well by her nickname, Ani, was first lady from 2004 to 2014. Her husband became Indonesia's sixth president after winning the country's first-ever direct elections for head of state in 2004 amid high expectations that he would fix the many problems saddling the world's most populous Muslim nation, among them rising Islamic militancy, massive poverty and widespread corruption.

Her father, Sarwo Edhie Wibowo, was an Indonesian military leader who played a role in directing troops during the Indonesian army's extermination campaign that killed several hundred thousand civilians during anti-communist hysteria in the mid-1960s.

She was appointed as vice chair of the Democratic Party and she campaigned for the election of her husband for president.

During her era as first lady, she organised polio immunisation campaigns and "Smart Cars," in which vans were filled with books for children to read across the country. She also assisted in relief efforts when a massive earthquake hit Indonesia in 2004 and spawned a giant tsunami off Sumatra island, killing more than 230,000 people in a dozen countries - the majority in Indonesia.

She is survived by her husband, two sons and grandchildren.

Australian Associated Press