Former Indian prime minister Manmohan Singh has died at the age of 92.

Singh was one of India's longest-serving prime ministers and he was considered the architect of key liberalising economic reforms, as premier from 2004-2014 and before that as finance minister.

He had been admitted to a hospital in the capital Delhi after his health condition deteriorated, reports say.

Singh was the first Indian leader since Jawaharlal Nehru to be re-elected after serving a full first term, and the first Sikh to hold the country's top post. He made a public apology in parliament for the 1984 riots in which some 3,000 Sikhs were killed.

But his second term in office was marred by a string of corruption allegations that dogged his administration. The scandals, many say, were partially responsible for his Congress party's crushing defeat in the 2014 general election.

Singh was born on 26 September 1932, in a desolate village in the Punjab province of undivided India, which lacked both water and electricity.

After attending Panjab University he took a master's degree at the University of Cambridge and then a DPhil at Oxford.

While studying at Cambridge, the lack of funds bothered Singh, his daughter, Daman Singh, wrote in a book on her parents.

"His tuition and living expenses came to about £600 a year. The Panjab University scholarship gave him about £160. For the rest he had to depend on his father. Manmohan was careful to live very stingily. Subsidised meals in the dining hall were relatively cheap at two shillings sixpence."

Daman Singh remembered her father as "completely helpless about the house and could neither boil an egg, nor switch on the television".