A fifth executive is understood to have been suspended by Tesco as Britain’s biggest retailer investigates the £250m overstatement of its profits.

The Financial Times reported that the group commercial director, Kevin Grace, was asked to step aside on Monday, although Tesco declined to comment. Grace has been on the retailer’s executive committee since December 2011, having joined the group in 1982.

Just three weeks after its new chief executive, Dave Lewis, took the reins, Britain’s biggest grocer stunned investors with the revelation that its profits had been artificially inflated by £250m.

Last month it suspended four executives, including the head of its UK food business), called in investigators and rushed in its new finance director, Alan Stewart, to help the supermarkets group get to the bottom of the accounting scandal. The City regulator, the Financial Conduct Authority, is conducting an investigation into the issue.

Tesco beefed up its board on Monday with the appointment of a former Ikea chief, Mikael Ohlsson, and the Compass CEO, Richard Cousins, as non-executive directors.

The Tesco board came under fire again last week after the embarrassing revelation that it had bought a $50m (£31m) Gulfstream corporate jet in 2013. Lewis, a former Unilever executive, is battling to stabilise sales after four profit warnings this year.

He is conducting a wide-ranging review of the business to stem the slump in sales, and is thought to be considering offloading Tesco’s Dunnhumby subsidiary.

Sky News reported on Monday that the private equity group TPG is among the suitors circling the marketing services group that created Tesco’s pioneering Clubcard loyalty scheme.