Griffith Police were called to Riverina Community College, where someone had taken to a building with purple spray paint sometime on Saturday night to draw an offensive image.

On Sunday night, three cars in Probert Lane were damaged with purple spray paint and on Monday morning, police were called to a business in Railway Street.

They found an expletive had been spray painted on the window of a business and found further graffiti on an adjacent business.

Police are also concerned about a spate of diesel thefts.

Griffith Inspector John Wadsworth said a large amount of diesel, along with a UHF radio and antennas was stolen from a worksite at Lake Wyangan.

A large amount of diesel was also stolen from a farm at Nerricon on Saturday, July 12.

"You have to be vigilant," Inspector Wadsworth said.

"Whether it's the spraypaint incidents or the issue of fuel being stolen, we all need to reamin vigilant.

"If you see anything that's out of place, you know your patch better than anybody. If you see something happening that you think is a crime in progress, don't be afraid to call 000."

Inspector Wadsworth said anyone with any information about suspicious behaviour should contact police.

"If anyone in the community has any information whatsoever, even hearsay, you can contact Griffith police and ask to remain anonymous or contact Crime Stoppers."