I won this Filipino movie on eBay today. As with so many of these films info, any kind of info, is scarce. The director is Cesar Amigo who also wrote the screenplay for THE BLOOD DRINKERS (1964) which is one of my favourite Filipino films. Charito Solis, Mario Monte and Fred Galang are all in the movie and according to the Greek seller (Onar-Bill) it is a:
[...] nasty exploitation revenge colossus, with tons of gratuitious violence plus some trashy fulci-ish gore, like acid on face that melts like a pizza!!!
I certainly hope he's right. xD
Here the original Filipino poster. Thanks to Andrew for making me aware of it. It comes courtesy of the amazing Video48 blog in the Philippines.