JK Rowling was surviving on £70 a week when she received the loan

The friend, who was not named by the author, gave Rowling the money when she was struggling to bring up a child on income support in Edinburgh.

Rowling told BBC Radio 4's Learning Curve the loan "was like half-a-million pounds to me at that time".

"It was an enormous sum of money," said the author - who has since become a millionaire as a result of her novels.

Studying

Rowling told presenter Libby Purves she was surviving on £70 a week as a single mother and studying to be a teacher when she was offered the loan.

The extra money helped provide child care for her daughter, Jessica.

"I broke down and cried when my friend offered it to me," said Rowling.

"We both thought I'd never be able to pay it back. In effect my friend was saying: Here's a gift to help you."

Monday's Daily Telegraph newspaper reports the loan came from a female friend in Edinburgh, who was later given a two-bedroom flat in the Scottish capital by Rowling.

The 39-year-old author, who has sold more than 250 million books around the world, was recently named as the world's best paid author on Forbes magazine's billionaires list, published in the US.