The Guardian newspaper's addition to the council follows the appointment of Richard Eyre as chairman of the IAB last week.
The appointment of The Guardian is seen as significant because of its position as a key traditional media heavyweight.
The Guardian is expected to take the lead on developing standards for online advertising, drawing on its expertise from press. Its team will also develop best practice for integrating marketing campaigns across multiple media channels.
The IAB leadership council is the strategic body that tackles the major issues facing the industry and is leading the charge to double online media's market share by autumn 2004.
In the last few months, more senior figures have come forward to play their part in pushing the industry forward via an expanded IAB leadership council.
Simon Waldman, director of digital publishing at Guardian Newspapers, said: "As the owner of the UK's most popular newspaper website, we have long believed in the value of new media -- both to us as publishers and to our advertisers."
The IAB now includes boasts senior executives from AOL, Ask Jeeves, Associated New Media, Freeserve, Google, Channel 4, Lycos, MSN, Overture, Real Media, Value Click, Yahoo! and Yell.
Danny Meadows-Klue, IAB chief executive, said: "This is a tangible signal that traditional media is taking online seriously, putting its weight behind the industry, and committing to doubling share of all media spend."
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