Teams including former officers from the British Brigade of Gurkhas were seen on the Falls and Shankill Roads on Wednesday.

Everest Security, which employs the Gurkhas, has been hired by National Car Parks (NCP) to cut the number of untaxed cars on the road.

Councillor Jim Rodgers, the Lord Mayor of Belfast, said: "I find this absolutely unbelievable. I am flooded with complaints about National Car Parks and their lack of discretion and sensitivity. This is getting totally out of hand.

"I'm rather amazed that there was no indication that this was going to happen. This is a great, great surprise and I would ask NCP to explain themselves."

Tim Cowen of NCP said the Gurkhas were being used to "advise our staff on safety and security" and had been used in similar operations across the UK.

"Sometimes if you are clamping an untaxed vehicle, the owner may get confrontational and we need to be very careful in ensuring our staff are safe."

He said although the teams were "mostly" ex-military, he did not believe the security situation in Ulster made their deployment insensitive.

"What they have done in previous careers is not something we need to be concerned with."

He said the teams, including Gurkhas, had been working in Belfast for "a couple of days" and that they would work in Belfast before moving around the province.

But he refused to name the areas of Belfast the operation was focusing on. "We are targeting those areas in Belfast with high levels of tax evasion but if we name those areas, the untaxed vehicles tend to disappear."

Sinn Fein councillor Gerard O'Neill said people in Northern Ireland had " had their fill" of the Army.

"However, obviously these Gurkhas are not coming in as British Army soldiers," he added.

Acknowledging that there was a tax evasion problem in west Belfast, he urged NCP to treat the public with fairness in enforcing traffic regulations.

NCP was awarded the contract by the Driver Vehicle Licensing Northern Ireland (DVLNI) in May last year to take more untaxed and illegal vehicles off the road.

DVLNI said it hoped the scheme would help fight crime, antisocial behaviour, burglarly and the violence he claimed "drivers of untaxed cars tend to be involved in".

Gurkhas are Nepalese soldiers best known for their role in the British Army's Brigade of Gurkhas.

NCP took over police traffic warden duties last October.