In a statement, the three judges of the non-fiction category of the biennial Singapore Literature Prize condemned a National Library Board (NLB) decision last week to pulp three titles that went against its "pro-family" stance.

"We condemn in the strongest terms NLB's decision to remove and destroy these books, given that it is responsible for the dissemination of information rather than its destruction," said T. Sasitharan, Romen Bose, and Robin Hemley.

The trio are prominent figures in Singapore's small but vocal arts and literary community. The Singapore Literature Prize is considered the city-state's most prestigious writing award.

The state-funded NLB last week confirmed that three titles would be destroyed following complaints by a parent and an internal review.

They include "And Tango Makes Three" -- a true story about two male penguins in a New York zoo that raised a baby penguin -- and "The White Swan Express", which features children adopted by straight, gay, mixed-race and single parents.

The third book, "Who's In My Family", discusses different types of families, including references to gay couples.

The decision to destroy the books was supported by Singapore's information minister Yaacob Ibrahim, who said the NLB was "guided by community norms" which do not support teaching children about "alternative, non-traditional families".

Singaporean writers however slammed the NLB for partaking in "book burning" and censorship.

Some 400 people including parents gathered at a library branch on Sunday to read the banned books to their children as a show of protest.

A group of writers scheduled to speak at an NLB event on Sunday about humour also pulled out in protest.

In the statement Wednesday, the three judges said the planned destruction of the books was "bigoted and sets a very worrying precedent that it is acceptable to discriminate against anyone who may hold differing values and opinions".

The move was "unbecoming of an institution entrusted to protect and preserve learning and literature and to provide accessibility to information," they added.

The books episode has sharpened the split between Singapore's religious conservatives and its growing gay-rights lobby, which staged a peaceful rally attended by more than 20,000 people on June 28.

Sex between men is illegal in Singapore and punishable by up to two years in jail under a provision in the penal code dating back to British colonial rule.