Consumer campaigners say that the number of people opting to switch banks is still too low as new figures show that over 600,000 current account holders have swapped providers in the six months since a new guarantee to make it easier to move was launched.

The Payments Council, which is overseeing the new service, said there were 609,300 switches in the six months to the end of March, which represents a 14% increase on the same period a year earlier.

But Which? said that despite more people becoming aware that switching banks is easier than it has been in the past, the new guarantee has not been a "game-changer" in terms of prompting people to ditch their old bank.

Which? executive director Richard Lloyd said: "Despite an increase in public awareness and confidence, switching levels are still low, suggesting that the new seven-day service is not the game-changer that can significantly increase competition in banking."

Under the switching guarantee, the bank or building society the customer is going to arranges for all existing incoming and outgoing payments to be transferred with the old account then automatically closed.

The new service is free to use for consumers, small charities, small businesses and small trusts and the Payments Council said more than 99% of switches that successfully start are completing in the seven-day timescale.

But the Federation of Small Businesses (FSB) said more work is still needed to make the process run smoothly.

John Allan, national chairman of the FSB, said: "In some cases, switching accounts has taken longer than expected with much of the leg work being undertaken by the businesses rather than the bank."

The Payments Council has said that switching levels on their own are not deemed to be the best measure of success. Its figures show more than two-thirds of people (67%) in the UK are now aware of the switching initiative, which is up from 59% at the end of 2013.