The alerts, which are believed to have been sent in error as part of the latest round of glitches at the stricken platform, called advisers to act on the news or risk breaking regulatory rules.
It is a requirement under European regulation the Markets in Financial Instruments Directive (MiFID II) to inform clients when their discretionary managed portfolio has dropped by more than 10 per cent since the last quarterly statement.
The note from Aviva for Advisers read: “Please be aware that the following accounts have dropped in value by more than 10 per cent.
“MiFID II regulations require clients to be informed of this loss by the close of business on the day of notification.”
Scott Gallacher, director at Rowley Turton Private Wealth Management, said emails were sent on the weekend to what appeared to be all his clients on the Aviva platform.
He said he had called Aviva on Monday morning but could not ascertain whether any letters had been sent to the clients directly.
He said: "Despite ringing Aviva this morning they are still unable to confirm whether or not this was sent to clients either by e-mail or post.
"This in itself is extremely unsatisfactory as I don’t know whether I should be proactively contacting clients just to head off the inevitable concern."
Jamie Flook, financial planner at Trigon Pensions Limited, said all his clients on the Aviva platform were affected by the glitch but he was told by his representative the issue was being investigated.
He does not think clients have been contacted directly but he said it was “worrying” the platform appeared to have come up with random numbers for losses.
Mr Flook found one of his clients' portfolios had lost 1.5 per cent in real terms but the notification had told him it was 28 per cent.
He said: “It's pretty worrying that they can seemingly pluck random numbers out of the air for their returns notifications.”
Another adviser, who does not want to be named for fear of prejudicing his ongoing dealings with the insurer, also received the notifications, which told him his clients had seen their portfolios drop by up to 59.8 per cent.
He said: “You can see that must be a mistake but they haven’t told us anything about it. I should be going through every single portfolio and check otherwise I might be breaking regulatory rules.
“The notifications went out on Saturday. They could have sent us an email to say that was a mistake. The communication has been atrocious.”