Lending a car for a friend’s wedding may lead to jail time. The Transport Department has sent letters to Adelaide residents who had lent their vehicles to other people for a wedding, threatening to prosecute them.

According to the government agency, it is illegal to run transport passenger services without accreditation, and that may include lending a vehicle to other people for an event.

Vintage car owner Kevin May was one of the receivers of the letter. He told ABC News that he was threatened to be prosecuted for lending his 1969 XW FT Falcon to a family friend for a wedding.

“I was quite upset about it at first – I thought it was a joke – and then when I studied the letter properly, you could see it had numbers on there and it was definitely an official letter and I thought ‘God, blimey Charlie, I was only trying to help someone out,” he told the news site.

Mr May was told that he could face penalties of up to four years of jail or a $15,000 fine. He wants the warning to be withdrawn immediately as he said it is an infringement of his human rights.

Family First MP Robert Brokenshire also wants the warning sent to his constituents to be dropped.

“It’s one thing to be out there catching rogues... that are impersonating accredited hire car companies but when a family friend lends the Subaru or the Ford Falcon to a friend for a wedding and they receive a demanding prosecution letter, it’s absolutely outrageous,” he told ABC.

“I mean this is absolutely wrong. A person should be able to lend their car legitimately to a friend for a wedding without intimidation or fear of a fine or prosecution.”

Bill Gonis, manager for passenger transport from the Transport Department, defended the letters, saying that they were only to inform people what was legally allowed.

“It’s a letter of warning and advising them if they want to speak to someone at the office we are more than happy to help them with any inquiry they may have,” he explained.

“If they’re simply just providing that service for a friend of theirs that’s fine, that’s the end of that. Again I just have to make that clear that we’re not prosecuting people who are simply driving their friends around.”

Mr Gonis added that the warning letter was really about ensuring public safety and ensuring that the vehicles being lent are roadworthy.