A Liberal National party official has rallied supporters for the Queensland election by accusing Labor rivals of “dirty tricks” in past campaigns including the criminal offence of impersonating police officers.

The LNP state director, Brad Henderson, in an email calling for volunteers said Labor in recent elections had “tried every dirty trick in the book ... including enlisting the unions to dress people up as firemen, nurses and policemen”.

However, a spokesman for Queensland police, as well as senior police sources, said they were not aware of any such incidents involving the misuse – or even use – of police uniforms in political campaigns.

Henderson’s claim followed a series of niggling exchanges between LNP and Labor camps that led to the involvement of police on the hustings in Brisbane.

This included the alleged theft of a Labor candidate’s sign by a Young LNP member and this week’s arrest of a man who wore an “I’m with stupid” t-shirt among LNP supporters which made worldwide headlines.

Under the police service administration act, any non-police officer caught wearing a uniform is liable for a fine of up to $11,385 – with the exception of entertainers, people wearing fancy dress for balls, carnivals “or similar occasions”, or those who have permission from the commissioner.

A senior police source told Guardian Australia that “no police officer in uniform, let alone a person dressed in a police uniform, has been involved in handing out material as part of any recent election”.

A spokesman said Queensland police were not aware of any complaints relating to the wearing of police uniforms in political campaigns, although they could not categorically rule out it ever having occurred.

Henderson did not respond to questions by email from Guardian Australia.

In his email to supporters titled “we need you”, Henderson said: “To win this election we need each and every one of our supporters to stand up and assist their local campaign.”

“In recent elections, Labor has tried every dirty trick in the book ... including enlisting the unions to dress people up as firemen, nurses and policemen,” he said. “We aim to fight these dirty tricks with our positive efforts.”

The United Firefighters Union has previously rejected LNP claims it organised fake uniforms for Labor campaign supporters in the Redcliffe byelection last year, insisting its members were “real firefighters”.

Henderson’s letter was sent out on Friday as police were investigating a complaint of a Young LNP member stealing a campaign sign from Kallangur Labor candidate Shane King.

An LNP spokesman told Fairfax that the party was aware of the sign incident was treating it “very seriously”.

“The LNP in no way condones theft,” the spokesman said. “The matter is now under [party] investigation and the person concerned faces disciplinary action, if proven.”