The warning came ahead of a joint RCGP and Faculty of Sexual and Reproductive Healthcare (FSRH) statement on the future of LARC training due later today.
GP understands the college and faculty will announce plans for a new LARC training package for GPs and other health professionals following two years of talks.
LARCs - including copper intrauterine devices, progesterone-only implants and vaginal rings - have a far lower failure rate than oral or barrier contraceptives but are used by only 12% of women in Great Britain.
An investigation by GP in 2010 found one in three practices were still not allowed to provide LARCs by their PCT, although LARC provision was improving.
Over the past six years, 3,910 faculty members have been trained to fit intrauterine devices and 4,825 to fit sub-dermal implants, although members can acquire both qualifications.
There has been a steady rise in qualifications since 2005, yet senior doctors say this must improve further if more women are able to have LARCs fitted.
FRSH president Dr Chris Wilkinson told GP: 'A real concern of the faculty is the commissioning of enhanced services, which I'm advised by many of our senior GP members are being cut back. If there are no mechanisms for payment it is quite difficult to consider why [practices] would provide these services in reality.'
RCGP spokeswoman on women's health Dr Sarah Jarvis claimed 'the big issue' with LARC fitting was that previously there has 'appeared to be a lack of national policy' on GP training.
Speaking to GP at the MIMS Women's Health Conference in London last week, she said a lack of trainers was a 'consistent issue' that was a 'rate-limiting factor' in progress to improve uptake of LARCs.
Dr Wilkinson denied there is a shortage of trainers. Instead, he said, PCTs are simply not commissioning those trainers that are available to teach GPs. 'In some areas, there's been a lack of investment for many years and training doesn't stay at the top of the priority list,' he said.
'We have to ensure there is investment in training and not disinvestment in enhanced services, to ensure the mechansims to fund these services to be delivered in general practice are there.'
Dr Wilkinson said these shortcomings are likely to be holding back LARC provision. 'The more you make LARCs accessible through general practice, the more people will take it up.'