Around 200 local police officers protested outside Valencia's town hall to complain about a shortage of vehicles and equipment.
Also present at the demonstration were several 'go-go' dancers in underwear and union t-shirts, a move designed to highlight the city force's lack of new uniforms.
One brave officer turned up in bright blue long johns, Spain's El Mundo newspaper reported.
Police were using 30-year-old pistols, their bullet-proof vests were out-of-date and safety equipment for motorbike police was lacking, union officials told reporters.
The protest comes after an accident which saw four officers receive light injuries when the 17-year-old van they were travelling in allegedly suffered brake problems.
But Valencia's town hall has dismissed officers' claims, saying the driver of the van was at fault.
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An official said the city's local police force had "everything it needs to carry out its duty," 20 minutos newspaper reported.