This tree may be the same one named Calophyllum wallichiamum and described in the Digital Nature Archived of Singapore website. However, I was not able to locate any other reference in the Internet on this botanical name. Instead, there were a lot of reference on the name Calophyllum lanigerum and its pictures.
The fruits below were found on the ground near one of the tree. As I had not seen the fruits on the tree itself, I could not really tell whether they belong to this tree but they did look like fruits from a Calophyllum species.