BBC Wales political reporter
The Office of Fair Trading (OFT) has been asked to investigate a car parking company accused of "extortionate" price increases in Cardiff city centre.
Traders fear Cardiff's reputation will be damaged by the charges
Drivers now pay 80p per 15 minutes, up to a £12 maximum, in one NCP car park and retailers fear trade will suffer.
Welsh Conservative MEP Jonathan Evans said the company's actions in Cardiff may be the "right signal" for a UK-wide inquiry into the UK car parking market.
NCP has been asked for comment on Mr Evans's call for an investigation.
Businesses in Cardiff city centre reacted furiously when the price increases were introduced in several of NCP's multi-storey car parks across the city centre.
Cardiff Central Liberal Democrat MP Jenny Willott raised the issue in the House of Commons warning the "extortionate" price rises could put people off coming to the city.
Now Mr Evans, a competition minister under the previous Conservative government, has written to OFT chief executive John Fingleton.
He has expressed concern over the current position in Cardiff and questioned whether other major cities had seen similar huge price hikes.
Mr Evans said: "I am all in favour of open competition, but the close relationship between NCP and many local authorities leads to real concern that both have an interest in driving up prices to the consumer.
"It seems that the structure of the market in city centre car parking throughout the UK may not have been investigated for some time.
"So the recent row over NCP's actions in Cardiff may be the right signal for the Office of Fair Trading to analyse and re-examine that structure."
In his letter Mr Evans, said that some of the charges had increased by more than 100% in Cardiff at the same time as a "significant reduction" in city centre parking spaces because of major redevelopment work.
Cardiff Council leader Rodney Berman denied any suggestion that the authority supported NCP's price increases and said he had both written to and met the company to express his concerns.
He said the charges had increased to "very steep levels" in recent years to increase NCP profits.
Mr Berman, a Liberal Democrat, said that the decision by a previous Labour administration to give up the council's power to limit price increases meant there was little the authority could do to control the multi-storey charges.
Mr Berman admitted the council had increased its own parking fees but said extra revenue raised had been used to improve enforcement of traffic regulations to the benefit of the city.
The Office of Fair Trading said it could not comment on individual cases.
A spokesperson said: "When we receive a complaint, we consider whether or not it requires further action."
NCP has been asked for a comment.