A government probe into alleged abuse of Japan's public health insurance system by foreign residents has sparked controversy, with critics claiming the investigation encourages prejudice against non-Japanese.

In January, the health and justice ministries began looking into allegations foreigners had fraudulently obtained residential status in order to join the nation's public insurance system as a way to avoid paying costly medical fees. The move followed concerns raised by medical workers that abuse of the system could undermine the whole public insurance system.

But in the time since the probe was launched, no confirmed cases linked to fraudulently-obtained residential status have been found, prompting calls for the investigation to be terminated.