Labour has warned of a possible conflict of interest following reports that George Osborne has been advising the chancellor on his Budget while working for a City investment bank.
Mr Osborne, who served as chancellor between 2010 and 2016, held a meeting with Jeremy Hunt ahead of Thursday’s key autumn statement.
Labour said Mr Osborne should not be given access to "market-sensitive" information and urged the Treasury to disclose exactly what discussions he had been privy to.
Approached by The Independent, a Treasury spokesperson denied that Mr Osborne was providing economic advice and said the former Tory MP did not have access to sensitive information.
Mr Osborne has been employed by investment bank Robey Warshaw since February.
Treasury officials said the contact pre-dated the Budget and did not amount to “ongoing engagement”.
But shadow city minister Tulip Siddiq said she was “deeply concerned” that Mr Osborne had spoken to the chancellor and said it could pose a “potential conflict of interest”.
“Sensitive information on Treasury policy, if inappropriately handled, could result in insider trading, disorder in UK markets and put the economic security of the British public at risk,” she said.
Thursday’s statement will set out the economic course Britain will take under Rishi Sunak, and is likely to contain significant tax rises and cuts to public spending.
Such information is highly sought after by City investors looking to get ahead of the financial markets.
“The chancellor can’t just sneak his old friend George Osborne into the Treasury through the backdoor without any appropriate public scrutiny of his business dealings outside of parliament,” said Ms Siddiq.
“Any potential conflict of interest could have serious implications for the UK’s reputation as safe and fair place to invest.
“If this failing Conservative government has learnt any lessons at all from the market chaos and damage caused to the UK’s global standing in recent weeks, they must respond to the questions set out in my letter as a matter of urgency.
“If we were leading the autumn statement this week, Labour would be making fairer choices and putting forward our proper plan for growth.”
A Treasury spokesperson said: “The individual in question does not provide economic advice to the Treasury and has no access to market-sensitive information.
“All due care is taken to ensure members of the Economic Advisory Council – who attend in an independent capacity – are not privy to any material non-public information, or market sensitive information.”
MPs last month demanded an inquiry into possible insider trading resulting from Kwasi Kwarteng’s September mini-Budget after it emerged the then chancellor had met with various financiers before setting out his plan for the economy.
Prior to his resignation, there were reports Mr Kwarteng attended a champagne reception with hedge fund managers who were said to have “egged on” his plan to make £45bn of unfunded tax cuts – a plan which later sent financial markets haywire.
