SINGAPORE - The National Library Board (NLB) has removed two children's titles after it received e-mail complaints that the books are not "pro-family".

The first book, And Tango Makes Three, features two male penguins who behave as though they are a couple, while the second book, The White Swan Express: A Story About Adoption, has two female partners trying to adopt a baby from China.

Facebook user Teo Kai Loon had posted a note in a Facebook group named We Are Against Pinkdot In Singapore on Tuesday morning, calling on fellow group members to "scrutinise" the library's catalogue, and not allow such children's books to "go under the radar".

"You can always e-mail NLB for that, the action is swift, all within two days. Remember, the onus is on us," he said.

In the same note, he also included an e-mail he had received from Ms Tay Ai Cheng, NLB assistant chief executive. In it, she said that the two books have been removed following his feedback. She added that NLB takes a "strong pro-family stand" when selecting books for children.

"We have a collection of more than five million books. While we try to sieve through the contents and exercise our best judgment, it is an arduous task to ensure complete adherence of details in the books to our pro-family stand," she said in the e-mail.

"However, when library visitors like yourself highlight to us any conflicting content within books, we review such books thoroughly and withdraw them from circulation," she added.

Mr Teo's Facebook post was taken down as of 5pm on Tuesday, after it was shared on social media and attracted criticism.