I'm not familiar with your car specifically, but Nick is definitely correct in that you need to get the car scanned; here in the USA most auto parts stores will hook up their scanner for free. It's worth a try, although there's an even chance it may be manufacturer specific and could require a more advanced scanner.
That being said, one of the more common issues with ABS systems would be the wheel speed sensors. Being located on the wheels, they're subject to harsh environment and damage so it's entirely within the realm of possibility for either the sensor or the wiring to get damaged, so that's what I'd be looking at first, although again, a scan will point you in the right direction, whether that's the wheel speed sensors or not.