An independent national survey commissioned ahead of National Crime Stoppers Day on Monday revealed those who weren't prepared to speak up were held back by concerns for their own safety and feared repercussions.

Crime Stoppers Victoria chief executive Stella Smith said the research found a number of respondents second-guessed themselves before picking up the phone or going online to make contact, even though all types of crime information was welcomed.

"Of those people who said they weren't prepared to speak up, we found 65 per cent thought what they knew wasn't worth sharing, 36 per cent believed the crime information wasn't serious enough to share, and 19 per cent were held back because they didn't know if something was actually illegal or not," Ms Smith said.

"These moments of self-doubt mean some people in the community are not sharing potentially critical information about an unsolved crime or suspicious activity with us.

"We want people to know that even the most insignificant piece of information might be all it takes for police to solve a crime, and we welcome information about every type of crime, no matter how big or small."

Ms Smith said the theme of this year's National Crime Stoppers Day was 'Trust Your Gut'.

"Even though most people are self-isolating at home right now, they can still keep an eye out for something that doesn't sit right and speak up," she said.

"We want to empower people by reminding them that Crime Stoppers is here for everyone and every crime, every piece of information can make a difference and a safer community can be achieved by people contacting us."

To make a report, contact Crime Stoppers on 1800 333 000.

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