The decision means no one will go to jail in the UK over the scandal which has seen global banks fined billions by regulators.
The Serious Fraud Office has closed its investigation into allegations relating to the foreign exchange market due to “insufficient evidence”.
Banks have been fined billions of pounds in the last couple of years over the manipulation of foreign exchange rates.
But the latest decision means no individual will face a criminal prosecution for the scandal – which engulfed the City just as it was emerging from the shadow of the separate Libor rate-rigging affair.
The SFO launched an investigation into the forex scandal in July 2014 after a referral by the Financial Conduct Authority, the City regulator.
But its director David Green has now dropped the probe.
It said the decision followed a “thorough and independent investigation” lasting more than a year and a half and involving more than half a million documents.
The SFO said: “The SFO has concluded, based on the information and material we have obtained, that there is insufficient evidence for a realistic prospect of conviction.
“Whilst there were reasonable grounds to suspect the commission of offences involving serious or complex fraud, a detailed review of the available evidence led us to the conclusion that the alleged conduct, even if proven and taken at its highest, would not meet the evidential test required to mount a prosecution for an offence contrary to English law.
“It has further been concluded that this evidential position could not be remedied by continuing the investigation.”
The SFO said it continued to liaise with the US Department of Justice over its ongoing probe.
Last May, five banks including Barclays and Royal Bank of Scotland were fined atotal of £3.7bn after a US investigation into the forex market.
That followed settlements with US and UK regulators by lenders totalling more than 2bn in November 2014.
Separately, banks have also had to pay out over civil claims in the US brought on behalf of major multinational companies, pension funds and hedge funds which alleged that they were penalised by efforts to rig foreign exchange markets.
Source: SKY NEWS