Award-winning short story writer O Thiam Chin's first novel has bagged the inaugural Epigram Books Fiction Prize, Singapore's richest literary award.

The prize, announced in March this year, is for unpublished novels in English written by Singapore citizens, permanent residents and Singapore-born writers, wherever they are residing.

The 38-year-old O will receive a $20,000 cash advance against future royalties - the biggest-known advance promised to an English- language fiction writer in the Singapore publishing industry - and his book will be published by Epigram Books.

In his winning novel The Infinite Sea, a tsunami batters a coastal town in Thailand, leaving devastation - both physical and emotional - in its wake, as it tears two holidaying couples, their relationships already showing signs of fraying, from their partners.

O took four years to write the book, completing it last year. He beat three other experienced writers on the shortlist for the prize: award-winning author Balli Kaur Jaswal, playwright Wong Souk Yee - who stood in the recent general election and was elected Singapore Democratic Party chairman on Saturday - and author Sebastian Sim, who has published three Chinese sword-fighting novels under the pen name Yueguan Ming.

"It's like my first baby," O said of his novel, chuckling. "Winning such a big prize is unbelievable. It's outrageous! It makes the impossible feel possible. It makes me feel like I can do even greater things."

The author, who was on last year's shortlist for the Singapore Literature Prize for English fiction, has five collections of short stories to his name and, in 2012, won the Young Artist Award given out by the National Arts Council.

Between March 10 and Aug 31, Epigram Books received 69 entries sent in by 68 authors - one of whom submitted two manuscripts. These were eventually whittled down to four for the shortlist.

The winner was chosen by a blind reading conducted by a panel of four judges: Professor Philip Holden from the National University of Singapore's department of English language and literature, actress Janice Koh, best-selling author Adrian Tan and Epigram Books founder Edmund Wee.

"It really shows that, whatever people say, writing is not dead. People want to write - and they can write novels too, not just short stories. We expected a maximum of 20 novels. We got more than triple that," Mr Wee recounts animatedly.

He plans to make the prize a yearly affair and has his eye on eventually raising the award to up to $50,000. Epigram Books, he adds, plans to publish the three other books on the shortlist too.