A day after the Bank of England resumed its bond-buying in an emergency move to protect pension funds from partial collapse, Truss blamed the upheaval on Russia's invasion of Ukraine that has caused inflation to spike around the world.
"We had to take urgent action to get our economy growing, get Britain moving, and also deal with inflation, and of course, that means taking controversial and difficult decisions," she told BBC radio.
"But I'm prepared to do that as prime minister because what's important to me is that we get our economy moving."
Truss, Britain's 47-year-old former foreign minister, took office on September 6 after winning the governing Conservative Party's leadership contest, becoming the fourth prime minister in six turbulent years in British politics.
She defeated former finance minister Rishi Sunak by vowing to put an end to "Treasury orthodoxy" with a new economic policy that would cut taxes and regulation, funded by vast government borrowing to snap the economy out of years of stagnant growth.
But her fiscal plan, set out by finance minister Kwasi Kwarteng on Friday, triggered a crisis of confidence in the government, hammering the value of the pound and government bond prices and jolting global markets.
Truss said her government would not change course.
Having set out STG45 billion ($A75 billion) of unfunded tax cuts, she said it would in the coming weeks spell out reforms of everything from childcare costs to immigration, planning and financial regulation. A fuller fiscal statement on November 23 will detail the cost of the borrowing and measures to cut debt.
Investors and economists have said they cannot wait another eight weeks for details with borrowing costs elevated and markets volatile. As well as the risk posed to pension funds, the surge in borrowing costs has led to the withdrawal of cheaper mortgage offers and a leap in corporate lending rates.
The BoE's intervention had an immediate impact in driving down bond yields on Wednesday, but investors still see the central bank increasing rates by at least 1.25 percentage points to 3.5 per cent by November 3, the date of its next scheduled announcement.
Some are betting on an emergency increase before then, according to the prices of rate swaps.
Rates are seen rising further to 4.5 per cent in December and 6 per cent by June, levels that would likely hit house prices and offset any gains from a cut in property transaction taxes that was announced last week.
Economists mostly expect a less severe pace of rate increases.
"This is the right plan," Truss told the BBC. Asked if it was time to reverse course, she said: "No, it isn't."
Sterling pared some earlier losses to trade down 0.5 per cent against the dollar at $1.0797, taking its fall in September to almost 7 per cent and its fall year-to-date to almost 20 per cent.
Former BoE governor Mark Carney criticised the Truss plan, saying the release of only a "partial budget", without the accompanying scrutiny from the independent Office for Budget Responsibility, had unnerved investors.
"It's important to have (the budget) subject to independent and, dare I say, expert scrutiny," Carney said.
Kwarteng and Truss must now defend their strategy, and try to calm nerves in the Conservative Party which is due to start its annual conference on Sunday.
