Rachel Reeves has said tax rises and spending cuts are on the table for this autumn’s budget, as the government aims to tackle a growing shortfall in the public finances which she said was partly due to the lingering impact of Brexit.

Speaking to Sky News, the chancellor said: “Of course, we’re looking at tax and spending” as she prepared for her 26 November statement. “But the numbers will always add up with me as chancellor, because we saw just three years ago what happens when … the Conservatives lost control of the public finances, inflation and interest rates went through the roof.”

Asked if Brexit was to blame, Reeves cited “austerity, Brexit and the ongoing impact of Liz Truss’s mini-budget” as having an impact on her budget calculations.

“There is no doubting that the impact of Brexit is severe and long lasting,” she said. “People thought the UK economy would be 4% smaller because of Brexit.”

Reeves said ministers were slowly “undoing some of that damage” with the government’s recent EU arrangements on food, farming, youth mobility and energy trading, and with a priority of making deeper trade links, “most importantly with the EU”.

She said she wanted to be the “chancellor that gets stuff built in Britain” as she vowed to push ahead with plans to fast-track major infrastructure projects and overhaul Britain’s slow-moving planning system.

The autumn budget will mark Labour’s toughest fiscal test, after a downgrade in the productivity forecasts from the budget watchdog, the Office for Budget Responsibility.

Reeves confirmed the OBR had “consistently overestimated” the UK’s productivity, with the expected downgrade of its previous assumptions likely to make its task even harder.

With no boom in economic growth, stubbornly high inflation and the mounting costs of government debt, Reeves will have to fill a black hole estimated at about £50bn by some economists. This includes £6bn after the government’s U-turn on winter fuel payments to pensioners and its decision to drop cuts to the welfare budget.

Rachel Reeves said the planning and infrastructure bill was ‘probably the biggest piece of legislation that this government passes in the whole of this parliament’. Photograph: Stefan Rousseau/PA

The chancellor said her approach would be split between fiscal discipline to make the “numbers add up” and a planning offensive to push long-stalled projects over the line.

Asked repeatedly on the possibility of immediate tax rises, Reeves declined to rule them out or promise the cycle of fiscal tightening would end this year. She described a “doom-loop” in which weak growth limited fiscal headroom and forced further tax rises as something “nobody wants to end more than I do”.

Instead she insisted sustained economic growth was the only lasting solution, as it was “what brings in the tax revenues to be able to afford to keep taxes low and to invest in our public services”.

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The chancellor also pointed to recent figures that claimed the UK was the fastest-growing economy in the G7 in the first half of the year and business investment was increasing. But she acknowledged cost of living pressures “remain very real”.

Reeves used the interview to harden Labour’s builder-over-blocker stance, confirming backing for the Lower Thames Crossing linking Kent and Essex east of London, and promising to cut judicial review timelines by six months, with specialist judges assigned to complex cases.

She said the planning and infrastructure bill, which she called “probably the biggest piece of legislation that this government passes in the whole of this parliament”, was in its final stages. The bill would “swing the pendulum a little bit in favour, or quite a bit, in favour of those who want to get things done in Britain,” she said.

“The [Lower Thames Crossing] planning application has got 350,000 pages in it. That is longer than the complete works of Shakespeare. For getting a road built across the Thames, that is not acceptable. We used to be able to do things faster in the past.”