Due diligence processes have sparked a row, with providers taking an "unnecessarily" hard line, advisers have claimed.
Victor Sacks, director at VS Associates, said robust due diligence processes were to be applauded in cases where a scam was suspected - but argued providers should distinguish these cases from more conventional transfers.
Otherwise it risked damaging the adviser-client relationship over conventional business, he warned.
Mr Sacks said: “If a company wants to increase their due diligence and be more robust they could write to the client explaining they have been in touch with the adviser to verify their registrations and so on.
“But they should first write to the adviser, explaining their reasons for sending any letters, so the adviser has the chance to speak to their client. This way the adviser can ensure the relationship is not affected and the element of trust remains.”
His comments came after Gianpaolo Mantini, a chartered financial planner at Higgins Fairbairn Advisory, criticised Standard Life after it went directly to his client to request a call to discuss a pension switch.
Standard Life also demanded copies of recommendation letters and key documents - such as proposed investment details or fee structures - sent by Mr Mantini.
He said this decision, as well as the delay it would entail, was “unnecessary”. Mr Mantini had advised on the client's pension for five years, and Standard Life had previous experience of transferring money to the new provider, Fundment.
Mr Sacks added: “I would not have been happy with Standard Life approaching my client in this way.”
But David Brooks, technical director at Broadstone, said: “Too many times regulated advisers have been at the centre of pension scams. If providers can’t trust all advisers, then they must come from the position of suspicion as the default position.
"Providers have a duty of care to ensure the advice process has been followed properly and the receiving scheme is a bona fide scheme.”
He said he’d rather be “miffed” that a provider requested some more evidence, than just “rolled over to allow scammers to make hay”.
One long-running concern has been that not enough due diligence was carried out on investments held by self-invested personal pensions, which led to many consumers losing money and claims ending up at the Financial Services Compensation Scheme.
But advisers are now concerned too much due diligence can also have poor outcomes.
Phil Billingham, director at Perceptive Planning, argued providers should only be allowed to contact clients directly when there is a concern the funds will be placed in unregulated investments.
He said: “There should be a checklist of criteria which looks at whether the pension switch is done by a regulated adviser, staying in a UK regulated Sipp, and is going to normal, regulated funds.
“If this due diligence then flags the pension switch is being done to allow investments in unregulated funds, then the provider is right to write to the consumer directly without first going to the adviser to express their concerns."