Liz Truss, the favourite to become Britain's next prime minister, yesterday criticised rival Rishi Sunak over his tax policies while finance minister as the pair kicked off six weeks of campaigning.

The foreign minister wrote in the Daily Mail that "we have been going in the wrong direction on tax, with the tax burden at its highest in 70 years".

She promised to reverse recent rises and suspend green levies on energy bills.

Sunak oversaw the tax hikes as the UK battles to fix public finances after the coronavirus pandemic and amid spiralling inflation, and has accused those promising cuts of "fantasy economics".

The pair reached the final run-off to try to persuade some 200,000 party members after the last round of voting among Conservative MPs on Wednesday.