Around £2bn from the scheme will be used to encourage exports of green growth technologies, while a further £1bn has been earmarked for the defence industry.
Announcing the fund, Chancellor Rishi Sunak, said: “This decade will provide even more opportunities for British businesses to export and trade with new partners across the world.
“The Government will support business to seize these opportunities and thrive on the world stage.
“This package – which is the highest level of export lending the Government has ever made available – will provide support to industries and regions across the country.”
The announcement came amid a flurry of proposals from the Treasury ahead of a Budget which is expected to be dominated by the Government’s response to the unfolding coronavirus crisis.
Overnight the Treasury announced that the set-piece fiscal event will also include a £70m pot to make community sentences tougher for offenders, including the nationwide roll-out of ‘sobriety tags’ which alert police when criminals with alcohol problems drink.
A further £30m is set to be committed to tackle domestic abuse and provide extra support for rape and sexual assault victims.
Mr Sunak said the cash would be used to hire independent sexual advisers to help victims through the justice system, while a further £5m will be used to trial a new domestic abuse court.
“Keeping our streets safe is one of the people’s priorities – we are already delivering on this by hiring 20,000 new police officers and building 10,000 new prison places,” he said.
“At Budget we will go even further with new funding to toughen up community sentences, crack down on domestic abuse and provide victims with the support they need.”
Other announcements made ahead of Wednesday’s Budget include a £50m fund to improve accessibility for disabled commuters at 12 stations across England and Wales.
A further £30m has meanwhile been earmarked to build swathes of new fully accessible toilets at public buildings around the UK.