The president of Toshiba Corp., which has been embroiled in an accounting scandal, placed intense pressure on his subordinates to meet profit targets, potentially driving them to pad profits, sources familiar with the matter said Friday.

President Hisao Tanaka made phone calls and sent emails to his subordinates early in the morning in some cases, demanding they improve business performance, and some exchanges could be taken as calling for irregular accounting, the sources said.

Toshiba also called its profit targets a "challenge" or "stretch," with the latter apparently used to describe more ambitious targets, they said.

The third-party panel formed to investigate accounting irregularities is expected to look into whether Tanaka and his predecessor as president, Norio Sasaki, who currently holds the post of vice chairman, played any role in causing the scandal.

The accounting scandal could increase calls for Tanaka's resignation, as Toshiba's padded operating profits may reach ¥200 billion ($1.6 billion) over five years to March 2014.

Sasaki had a similar management style, and is believed to have also pressed subordinates to achieve profit targets while company president. According to the sources, he sometimes pressed them hard, uttering harsh words like "Why can't you just get it done?"

Sasaki served as Toshiba president between 2009 and 2013, covering most of the period during which the company has been found to have overstated its profits.

To take responsibility for the scandal, Sasaki may step down as a board member at an extraordinary shareholders' meeting scheduled for September, and as a vice chairman of the Japan Business Federation, or Keidanren, the sources said.

Both Sasaki and Tanaka are believed to have rejected the accusation that they instructed subordinates to pad profits.