Bogus gas men 'swindled thousands' out of expatriates, pensioners and the disabled across the country

A total of 60 gas inspection companies have been uncovered so far and 12 people arrested, mostly in Valencia and on the Costa Blanca, in Andalucía and the Balearic Islands but also in Madrid, Catalunya, Galicia, Castilla-La Mancha and Castilla y León.

They would turn up on spec at people's houses – mostly those they felt would be a 'soft target' such as expats, the elderly or disabled – and said they were there to carry out the regular mandatory inspection on their gas bottle connections.

If the homeowner refused, the suspects would threaten them with huge fines.

They charged anything from 50 to 390 euros although on at least one occasion, up to 2,500 euros.

On several occasions, they frogmarched elderly homeowners to cashpoints and stood over them while they drew out the required cash.

The arrested parties lived a very wealthy lifestyle with several properties apiece in Spain, and investigations have led to the confiscation of at least 10 top-of-the-range cars and the freezing of 227 accounts in 19 banks.

All the companies in question were set up as legitimate gas maintenance firms, but their activities were totally illegal and the certificates they issued following installations – such as fitting new rubber pipes – and for 'inspections' were completely invalid.

In most cases, gas boards who were contacted had to carry out subsequent inspections to ensure the accused parties had not tampered with the gas and made it unsafe, either deliberately or unintentionally.

Some of the suspects purported to be from gas companies such as REPSOL, carried fake company ID and wore orange and black overalls which appeared to be the firm's uniform.

Many residents on urbanisations home mostly to expatriates in coastal areas have reported similar door-to-door attempts to inspect their gas and even telephone calls trying to arrange visits.

Those who have been targeted before have often sent them away with threats of calling the police, and on one occasion in 2005, residents on an urbanisation on the Costa Blanca surrounded the 'gas men' with a human chain, preventing them from escaping until the police arrived.

Anyone whose gas bottles are delivered on a contract basis from firms such as REPSOL will receive a letter every five years inviting them to contact the company directly either by telephone or in person to arrange an appointment.

The paperwork issued once the money has been paid – typically around 60 euros – shows REPSOL's stamp and is valid until the next letter arrives.

All legitimate gas engineers will show their company ID at the door and will not be offended if homeowners make them wait while they call the gas board to check their authenticity – in fact, genuine engineers will actually be thankful for homeowners doing this, since they too want to see bogus inspectors stopped and are keen for residents to exercise all due caution.

Where gas is not delivered on a contract basis but is purchased directly from petrol stations, for example, installations still need to be inspected every five years.

In this case, exactly the same as for contract customers, no maintenance engineers will call at the door or by telephone and the homeowner should approach a recommended and qualified company to carry out the works.

REPSOL can recommend these or send out one of their own engineers if requested.

Rubber pipes sometimes need to be replaced, and the cost of doing so is negligible – anything from a few cents but never more than five euros, and is a split-second operation which should not attract hefty labour charges.

Anyone having a gas inspection carried out should agree a price before the maintenance person starts work, or they may be legally liable to pay even where the inspection is uninvited.

Attempts at fraud by bogus gas men, either suspected or proven, should always be reported to the police and the gas board.