Personal finance guru Martin Lewis has flagged up a savings account offeringt the best rate of interest - but said it's the best of both worlds. Speaking on his BBC podcast the Money Saving Expert founder warned that it 'won't be around very long.'.

He said the deal was for a fixed one year savings account at an interest rate of 4.55 per cent. But not in common with other fixed accounts people can access the money in an emergency.

Mr Lewis explained: "There's a new top savings account a little bit different so I thought I should tell you about it. Just wanted to mention this as it's quite interesting and we don't often see it.

"There is a savings account atthe moment that is arguably the best of both worlds. It's the top one year savings fix so you can lock your money away and earn 4.55 per cent guaranteed for one year which is normally why you go to a fix.

"The cost of a fix is normally that you can't withdraw your money so you have to be committed to locking it away totally. The interesting thing about this Marcus 4.55 per cent one year fix - Marcus is an app-based bank so you have to open it through an app. It's part of Goldman Sachs so part of a very big bank, you can put £250,000 a year in there, you only need a minimum of £1."

The personal finance expert said there was something unusual about the account: "It unusually gives you the flexibility that if necessary you can withdraw money during the fixed term. Now to do that you actually have to close the account and you would lose 90 days of interest, although if you close it within the fist 90 days you'd just lose any interest you would have been paid up to that point.

"So it's not the accountfor those people who would willy-nilly want to take money out. But anyone who wants to put money away in a fix has a slight worry about doing so just in case they have an emergency and they need to access that money then it becomes a very good option because you're going to get 4.55 per cent and in that emergency you could actually get the money out.

"I don't think it's going to be around very long though - they've said it could go at any time." Anyone interested in the account can visit https://www.marcus.co.uk/uk/en/savings (at time of publication it was still live).

Meanwhile Savers could end up having less money to put into stocks and shares if the cash Isa limit is cut, a finance expert has said.

The comments follow speculation that plans to cut the annual tax-free cash Isa allowance could be announced in Chancellor Rachel Reeves's Mansion House speech on July 15.

The Government is looking at options for reforms to Isas to get what it feels is the right balance between cash and equities, to help savers earn better returns, boost the culture of retail investment, and support the push for growth.

The Financial Conduct Authority (FCA) has previously said there are around seven million adults in the UK with £10,000 or more in cash savings who may be missing out on the benefits of investing throughout their lives.

Sarah Coles, head of personal finance at Hargreaves Lansdown, said: "Cash Isas are often a first port of call when people are starting out, and they'll often gradually move over into investments as they find their feet.

"If the speculation is accurate, it means they'll have less available to transfer into a stocks and shares Isa - effectively reducing investments rather than boosting them. This is an issue which requires a carrot not stick approach.

"We know through extensive research that the barriers to investing are behavioural, so it's through encouragement and increased confidence that we will all increase the number of retail investors.

"This week's announcement of radical changes to financial information, through targeted support and changes to the boundary between financial advice and guidance, is a major breakthrough in supporting people to find that confidence to make the first step."