Plans to increase Dublin's taxi fleet by 400 have been delayed after the Garda raised concerns about safety arrangements for disabled passengers.
The Garda's carriage office has refused to process further applications for taxi licences until the issue is clarified. Only 22 of 188 licences offered by Dublin Corporation have been issued.
In a statement, the Garda said it was "concerned that the safety arrangements for disabled people in wheelchair-accessible taxis are unclear and for that reason we are taking appropriate measures to ensure that any misunderstanding is removed. Therefore, we are unable to process further applications until this matter is resolved."
It is understood the safety doubts were raised following an accident over the Christmas period involving a taxi which had been converted to facilitate wheelchair-bound passengers. It is believed a passenger was injured in the accident and has since begun legal proceedings against the taxi company and the Garda.
The Garda has asked for advice from the Department of the Environment, which is examining whether converted taxis meet the requirements of EU safety legislation accepted by Ireland last April.
Meanwhile, the National Taxi Union said the delay was threatening the livelihoods of many drivers.
A union spokesman, Mr Vincent Kearns, said: "Unless it's resolved soon, we will be facing a major crisis. A lot of our members have already given up their jobs as co-drivers and have gone out and bought their own cars after they received their licence offers. They're now faced with keeping up with payments while they have no income."
