Mr Campbell is the highest profile witness so far
Tony Blair's former spokesman Alastair Campbell is to give evidence to the Iraq Inquiry next week.
When he appears next Tuesday, he will be the highest profile witness so far in the probe of UK policy in the run-up to the 2003 war and its aftermath.
Mr Blair will give evidence at a later date although his successor as prime minister, Gordon Brown, will not appear until after the general election.
The inquiry's final report is due to be published by early next year.
Mr Campbell, a former political editor of the Daily Mirror, was Mr Blair's press secretary from 1994 to 2003.