Banks will have the power to pause payments for up to four days to give them more time to investigate fraud, the government has said.

Currently, transfers must be processed or declined by the end of the next business day, but the new law will allow an extension of three more days.

For years, banks have needed to have reasonable grounds to suspect fraud before being able to investigate – but have also faced pressure from customers who want payments to be made instantly.

The long-proposed new regulations will come into force at the end of October – later than originally planned.

Fraud is the most common offence in the country, accounting for a third of all crime in England and Wales.

Criminals have stolen billions of pounds through romance scams or by impersonating a genuine trader to trick victims into transferring money.

“We need to protect these people better, which is why we are giving banks more time to investigate suspicious payments and break the criminal spell that scammers weave,” said Tulip Siddiq, the economic secretary to the Treasury.

Banks have lobbied for permission to take longer to agree to payments, to allow them to investigate suspicious transfers.

The new law will give them time to look at unusual spending patterns, contact a customer, and investigate further before the money is transferred.

The previous government’s draft legislation had proposed giving banks the new powers by 7 October, but now they will take effect from the end of the month.

UK Finance, the banking trade body, has welcomed the new rules. Consumer groups say the powers should be used in a careful and targeted way.

The changes could lead to some frustration among account holders who have become accustomed to bank transfers made online or via a mobile app going through almost instantly.

Banks will need to inform customers when a payment is being delayed, explain what the customer needs to do in order to unblock the payment, and pay compensation if the delay lands the customer with extra charges.

The rules will come into force a few weeks after the introduction of a stricter mandatory scheme that will see fraud victims receiving up to £85,000 in refunds from banks within five days of an authorised push payment scam.

The maximum compensation has been reduced from a previous proposal of £415,000.