O'Brien, who owns a 26% stake in the company, queried whether management would now look "equally hard at the cost structure of the group's international board", according to a report in the Daily Telegraph.
IN&M's five senior directors were paid a total of £7.97m, including bonuses and pensions, in 2007. Sir Tony O'Reilly, chief executive of IN&M, personally received £2.2m.
The newspaper publisher said yesterday that it plans to cut 90 jobs from The Independent and Independent on Sunday, with most of the cuts coming from the editorial department.
Affecting a fifth of the titles' 430 London-based staff, the changes are expected to be enacted by early in the New Year.
IN&M expects total savings from the restructure will be in excess of £10m.
Sales of The Independent and the Independent on Sunday have been in steady decline.
According to the October newspaper ABC figures, The Independent fell 16.29% in the year to October to record an average circulation of just 201,019 copies, while the Independent on Sunday hit a record low, down 21.4% year on year.