The Observer has claimed that Mitchells & Butlers chairman Simon Laffin has had his home and office swept for bugs in the latest twist in the row between the board and rebel shareholders led by billionaire Joe Lewis.
Security specialists called in to check for listening devices found nothing at Laffin's Surrey home and at M&B's offices in London and Birmingham.
But the move to order an electronic sweep of the premises illustrates the complete breakdown of trust between the M&B board and its biggest shareholders.
Laffin, who has chaired M&B for just 53 days, is expected to be ousted at M&B's annual shareholders' meeting at Birmingham's International Convention Centre on Thursday.
Lewis's investment vehicle, Piedmont, owns 23% of M&B and his associates, including Irish horseracing tycoons JP McManus, John Magnier, Derrick Smith and Michael Tabor, speak for another 22%.
Piedmont intends to remove Laffin and has put forward four new boardroom candidates, including former Debenhams boss John Lovering, whom Lewis hopes to install in place of Laffin as chairman.
Laffin insists the non-executives should represent not a small band of shareholders but all the group's 60,000 shareholders.
In an interview with the Observer, Laffin said: "It is a clash of two cultures. Lewis is thousands of miles away in the sun and he thinks he owns this business with his mates, while we are sitting here with lawyers and accountants and have to obey the rules."
The former Safeway finance director dismissed a series of issues raised by Piedmont about the management of the pub chain as "complete lies" and "crap".