A dog is believed to have been thrown off an apartment building by its owner, according to a neighbour who lives below the unit.

Facebook user Nina Zainal recounted the incident of the dead dog in a post shared on the social media site last night.

"I usually open my windows when I come back from work, because I have a cat.

"I was relaxing and watching the television when I heard something falling outside my window... I climbed the window to check what it was.

"To my horror, the neighbour above me threw their dog out," she claimed in her post.

She said she is certain that it was the owner who did this because after the dog fell, she heard someone closing their windows and the sound of footsteps running.

She immediately reported the incident to the security guards and lodged a police report, she added.

"I went upstairs and I shouted outside the house like a mad person because I was angry that they did this to an animal," she said.

In another Facebook post shortly after the first one, she uploaded a picture of a "blackmail" letter she wrote, which she slid under the front door of that house.

"I know what you did to the poor dog whom you've mercilessly threw out of your balcony.

"For what reason you did that, I don't want to know, because there's no reason to be that cruel to any living things," her letter read.

She also said in the letter that she had reported the owner to the police and the Society for the Prevention of Cruelty to Animals (SPCA).