The head of Britain's statistical watchdog has called on Prime Minister Rishi Sunak to be clearer about the source of his claims regarding the opposition

Labour Party's tax plans, suggesting he may have misled people about their independence.

Labour accused Sunak of lying during an election debate with its leader Keir Starmer on Tuesday. Sunak stated that "independent Treasury officials have costed Labour policies" and that these plans would result in a £2,000 ($2,560) tax increase for working households.

Sunak’s Conservatives are significantly trailing Labour in opinion polls ahead of the July 4 election. However, a snap poll following the debate indicated that viewers thought Sunak performed slightly better than Starmer.

The £2,000 figure Sunak cited, which represents a cumulative cost over four years, originated from a Conservative Party document that heavily relied on cost estimates from Treasury officials and Labour’s own calculations. Nonetheless, many key assumptions used by the Treasury about the implementation of Labour's policies were set by Conservative Party advisors in government.

Robert Chote, chair of the UK Statistics Authority, stated that the Treasury's costing of opposition policies has been a practice in British government since the 1950s, which he believes should be discontinued.

“This was a bad precedent when it started and we’d be much better off without it,” Chote told the BBC.

When asked if Sunak had been sufficiently clear about the origin of the figure, Chote responded: “When people get the wrong picture about the confidence, the independent verification behind this, that’s not a great place to be.”

Speaking to Times Radio, Work and Pensions Minister Mel Stride defended the Conservatives' £2,000 figure, noting that Labour had used a similar approach to Conservative policies when it was last in power in 2010. Photo by HM Treasury, Wikimedia commons.