Thousands of gas engineers remain untrained to the required F-Gas standards, according to training provider Develop Training.

The company's Mark Dougall said: "Many engineers did not comply with the July 2011 deadline [which demands that individuals are trained and certified] and many are now working illegally. We are worried about this for two reasons - not only could individuals be fined if they don't gain their qualifications, but we may also see a shortage of engineers able to legally undertake important servicing and maintenance work.

"We realise that many operators who have not yet undertaken the training may not even be aware of it, and there are also the timing pressures and cost factors."

It was these that led many engineers from small and medium enterprises not to take the additional legislated qualifications, according to a statement from Develop Training.

"However," it said, "it has also been noted that some of the larger companies employing gas engineers are trying to cut costs and corners by training some and not all of their engineers for the F-Gas Certification."

The statement added: "The legislation is part of the EU F-Gas Regulations, the first part of which was introduced in 2007. Since 2009, any company that employs engineers working under F-Gas Regulations must have a Company Certificate, but in July 2011 this was extended to individuals."

Mr Dougall said: "It is really quite shocking how many calls we are receiving from people who are as yet untrained. However, we realise that many may have put off undertaking this training due to concerns over downtime or expense.

"Part of the [Develop Training] course offers flexible E-learning to minimise the time impacts on small businesses, especially those independent business owners and small operators. In recognition of the time challenge, we are also offering a one-day assessment-only option."