Theresa May has insisted the UK can increase international trade while curbing immigration, saying a "world of opportunities" awaits after Brexit.
On a visit to India, the PM told the BBC businesses were "very keen" to strengthen their ties with Britain.
She played down the Institute for Fiscal Studies' warning about increased borrowing, saying the "fundamentals" of the economy were strong.
The IFS says future public finances have deteriorated by £25bn since March.
It said weak growth would lead to lower-than-expected tax receipts, increasing borrowing by £25bn by 2019-20.
Asked about this by BBC deputy political editor John Pienaar, Mrs May said the government was "determined to continue to live within our means", adding: "What matters is us taking the opportunities that are now open to us to develop trade around the world."
During her visit, Mrs May has faced questions about her twin goals of expanding the UK's global trade relationships after it leaves the EU while curbing migration, which the government wants to get below 100,000.
On Monday she said an expansion of the Indian visa rules would be considered if Indians who overstayed their visas in the UK could be returned more swiftly and in greater numbers.
Asked whether she was worried her crackdown on immigration could trigger a slowdown in trade negotiations, she said Indian businesses had told her they were keen to do business in the UK and that the Indian government wanted to "remove the barriers to trade and investment".
Once it leaves the EU, the UK will be able to strike its own free trade deals with other countries, with the government promising to make it a "global leader in free trade".
Such deals will involve negotiations on top of those involved with separating the UK from the EU, which are due to be triggered by the end of March 2017.
Mrs May predicted these talks would be "complex" but said she was "determined to grasp the opportunities for global Britain".