Fraud cases have increased by 16%, with scammers stealing more than £3million a day, according to banking industry figures.
Criminals particularly targeted their victims by tricking them into their one-time access codes, trade body UK Finance said.
Despite the increase in reported cases, total losses fell slightly, totaling £572 million in the first half.
Banks said fraud posed a “major threat” to the UK and called for support to tackle the crime.
The figures come after BBC Panorama earlier this week revealed a series of cases involving e-money company Revolut.
One victim told how she lost £165,000 from her business account in one hour. Revolut said it had “robust controls” in place.
Changes in fraudsters' tactics have led to an increase in cases in the first six months of this year, compared to the same period last year.
Unauthorized payments increased sharply, with losses up 5%, partly due to fraudsters bypassing protection systems.
When a customer makes a payment online, they often receive a one-time access code to verify the transaction.
Fraudsters have found ways to trick people into giving them these codes in order to steal money.
However, the latest data shows that there has been a relatively large decline in romance and investment scams.
This could be a result of the promise of stricter rules regarding the prevention of authorized push payment (APP) fraud.
When criminals trick their victims into sending them money by pretending to be a legitimate business, such as their bank or merchant, or by selling goods that don't exist, it's called APP fraud.
Mandatory new rules came into force on October 7 and will allow UK banks to reimburse victims of APP fraud up to £85,000 within five days.
Before the mandatory rules came into force, most banks had adhered to a voluntary repayment code.
There were 97,344 cases of APP fraud in the first half of the year, with total losses of £214 million.
“Fraud continues to pose a major threat in this country,” said Ben Donaldson, managing director of economic crime at UK Finance.
“In addition to the financial impact, this crime can cause serious psychological damage to victims.
“This is not a fight we will win alone.”
Charlie Nunn, chief executive of Lloyds Banking Group, on Sunday accused Meta, the tech giant which owns social media platforms Facebook and Instagram, of “enabling” people to be contacted by fraudsters running scams online.
Meta responded that its “Fraud Reciprocal Intelligence Exchange (FIRE) Pilot Program” was designed to allow banks to “share information so we can work together to protect people using our respective services.”
