Czech officials have vowed to force imitation vintage cars offering tourists open-topped sightseeing rides from the streets of Prague after nearly all of them were found to be dangerous and unroadworthy.

About 55 of 58 vehicles failed safety tests conducted by Prague city after complaints that they were clogging the streets of the Czech capital. Some showed shocking faults, such as home-welded parts, wheels fixed with a single screw and side mirrors designed for motorbikes.

The cars, supposedly representations of classic models of the 1920s and 1930s-era Czechoslovakian motor industry, have become an increasingly common sight in Prague, which is struggling to absorb a rising tide of visitors. They have come to be seen as symptomatic of the over-tourism that many residents say is blighting the city.

The vehicles, kitsch-looking and often bearing the inscription “Prague old car” on their doors, ferry tourists through the city’s most scenic areas in an attempt to re-create the feel of a bygone age.

In fact, most date from 2015 and 2016 and were manufactured in Poland.

Adam Scheinherr, Prague’s deputy mayor responsible for transport, said: “What we found is that these cars are dangerous. Their technical state is dangerous, they are a danger to nearby passing traffic and they are a danger to the passengers themselves.

Tourists on a sightseeing tour of Prague in a ‘vintage’ car. Photograph: Cum Okolo/Alamy

“They are not homogenised vehicles but have been cobbled together with parts of different vehicles. They are not made for the streets of a city but for a private setting like Disneyland.

“My officers have never seen anything like this. They were shocked at what they found. Never before have they found that 95% of vehicles inspected failed the tests.”

One car had a star-shaped symbol protruding from its wheel, which officials said could injure passers-by or cause collisions with other vehicles.

Some were found to have false documents, including being registered as ski-piste machines or forestry vehicles. One had been registered as an LPG motorcycle for six passengers.

“They were registered in this way to enable driving the car without complying with the technical parameters of a normal car, which raises questions not just about the owners, but about the permit-issuing authorities,” Scheinherr said.

Some cars have been confiscated after being towed away on police trucks. Others car owners were given a 30-day notice to repair technical problems or face losing their licence.

Tourists take photos as they ride in a ‘Prague old car’. Photograph: Tetiana Vitsenko/Alamy

Inspections also showed violations among other tourist vehicles, including hop-on/hop-off buses that had missing records of drivers’ driving times and breaks, and a “train” on wheels that emitted 200 times the legal level of emissions when its engine was ignited.

Officials will intensify the checks in the coming weeks before the peak tourist season ends in October.

The inspections have already had a deterrent effect on companies owning the cars, according to Scheinherr. He said: “Since we started the control, I see there are fewer and fewer pseudo-historical cars on the streets and I see advertisements putting them up for sale. On the advert it is written that the car is not suitable for business in Prague.”

Officials say their aim is to rid Prague of the imitation vehicles entirely.

Classic car rides have long been a feature of Prague’s tourist itinerary. But officials say authentic models have disappeared in recent years as businesses have been put off by their high asking price and maintenance costs.

Genuine Czech-made vintage cars cost an estimated €40,000 (£36,200), compared with between €12,000 and €20,000 for the imitation models.