Tony Blair is to be summoned back to the official inquiry into the Iraq invasion in light of damaging and conflicting evidence revealed since he appeared as a witness in January.

Members of the Chilcot inquiry are believed to be concerned about evidence in documents released in July showing that the former prime minister was warned by his government's chief law officer that an invasion of Iraq would be illegal the day before he privately assured George Bush he would support US-led military action.

The Guardian first reported in February shortly after Blair testified that the inquiry team planned to question him again in light of evidence which it was already clear contradicted that given by Lord Goldsmith, the attorney general at the time.

Documents released in July provided an unprecedented insight into how Goldsmith repeatedly warned the prime minister of the potential consequences of invading Iraq without fresh UN authority – much to Blair's irritation.

They included a note from Goldsmith to Blair, marked secret and dated 30 January 2003, saying: "In view of your meeting with President Bush on Friday, I thought you might wish to know where I stand on the question of whether a further decision of the [UN] security council is legally required in order to authorise the use of force against Iraq."

Goldsmith warned Blair that he "remained of the view that the correct legal interpretation of resolution 1441 [the last security council decision on Iraq] is that it does not authorise the use of force without a further determination by the security council".

Goldsmith concluded: "My view remains that a further [UN] decision is required."

A handwritten note, believed to be from David Manning, Blair's chief foreign policy adviser, warned: "Clear advice from attorney on need for further resolution."

Demonstrating his frustration with Goldsmith, Blair scrawled in the margin: "I just don't understand this." An aide wrote: "Specifically said we did not need further advice [on] this matter."

The following day, 31 January 2003, Blair flew to Washington for a meeting with Bush. Manning records the president – in a minute previously disclosed – telling Blair that military action would be taken with or without a second security council resolution and the bombing would begin in mid-March 2003.

The note records Blair's reaction: "The prime minister said he was solidly with the president."

On 14 January 2003, in a note handed to Blair, Goldsmith warned that UN security council 1441 "contains no express authorisation by the security council for the use of force".

By 7 March, after a trip to Washington, Goldsmith told Blair that a new UN resolution might after all not be needed, although going to war without one would risk Britain being indicted before an international court.

Ten days later, on 17 March 2003, Goldsmith published a short note saying an invasion would be lawful.