He told deputy minister Sumedha G. Jayasena about the book when she visited him on January 17.
Weerawansa said he would work late, until around midnight, and has so far written 24 pages.
He said the book, containing many revelations, would be printed and launched once he got released from custody.
Weerawansa most recently wrote a book titled ‘How good governance divides the country undivided by war’.
Previously, his ‘Neththa Wenuwata Eththa’ (Truth for untruth) earned controversy, with JVP secretary Tilvyn Silva filing a court case alleging a violation of intellectual property rights.
The case will be taken up again on March 10 by the Colombo commercial high court.