Swastikas and explicit racist messages have been sprayed on the walls of the underpass running below the A264 in Broadbridge Heath.
Vandals targeted the subway with images and phrases including ‘white power’, as well as anti-Islamic messages.
The underpass off Wickhurst Lane is regularly used by schoolchildren, who use it to travel between the village and Tanbridge House School.
Police are investigating the graffiti, which was removed yesterday (Monday January 26).
Inspector Clare McKnight of Horsham police said: “This is a very unpleasant but also very unusual and isolated incident.
“We have no records of any other such graffiti recently and there is no apparent connection with any local community.
“We work very closely with local communities and have reassured them that this isolated incident is being taken very seriously and fully investigated.”
Anyone with information can contact police via firstname.lastname@example.org or call 101 quoting serial 586 of 25/01. You can also contact the independent charity Crimestoppers anonymously on 0800 555 111.
The vandalism provoked anger on the County Times’ Facebook page.
Bill Smith wrote: “These disgraceful graffiti were no doubt sprayed on the walls by mindless idiots, who, no doubt don’t even know when the Second World War was, or even what white supremacy means. They most likely have a mental age of two.”
Kirstin McDonald added: “Disgusting! Obviously uneducated bigots, that have nothing better to do!
“They have no idea what it actually means. There is no excuse for racist bile like that.”
But Sabrina Gant pointed out the other historical meanings of the swastika symbol.
She wrote: “It’s also a religious symbol used by Buddhists and Hindus.
“The use of it by Nazis was at a 45 degree angle (diamond shape) so this symbolism is ironically promoting eternal goodness.”
Earlier this month, graffiti was discovered inside the Forum Car Park in Horsham town centre in what is believed to be a separate act of vandalism.
In December, Horsham District Council spent £950 on removing graffiti from the same car park.