It is not illegal if it comes fitted as standard, meaning
straight from factory. Not to be confused with locally fitted ones.
There are other governing rules on locally fitted ones and they
should be legal provided they adhere to certain rules on the
installation. But LTA also mentioned that foglight when NOT in use
should be covered up, so if u drive on clear weather with foglight
on or u drive without having them covered, u could be theoratically
booked for traffic violation. However no one seem to be caught for
that, so i guess LTA is closing 2 eyes and too lazy to review
legislation. 