Fidelity says it is currently the only fund supermarket which separately shows fund manager, adviser and platform charges.

The average cost of owning an actively-managed £10,000 investment is £16.67 per month or £200 a year.

This covers the cost of investment management, any advice given, provision of service and administration, dealing costs and stamp duty.

Gary Shaughnessy, UK managing director of Fidelity, described the current figures as ‘Ryanair pricing’ after the budget airline.

He said: “We are seeing selective and partial ‘Ryanair’ pricing start to emerge which runs the risk of misleading investors about the real costs they are paying.  A consistent way of showing charges is essential to restoring investors’ trust and encouraging them to feel confident to save for the future.”

He criticised companies who only presented part of their costs or had very high minimum investments.

“There are a lot of headline figures currently being bandied about but they do little to help investors understand the true cost of investing or to evaluate whether these costs are fair and reasonable for the service they are receiving.”

Mr Shaughnessy suggested a figure should be visible to consumers at the point of purchase and be represented as pounds and pence and as a percentage but that this format was open to discussion.