It was "tremendously important" for the public to hear claims that George Galloway took money from Saddam Hussein, a newspaper has said.
Mr Galloway has branded the story "outrageous"
Daily Telegraph executive editor Neil Darbyshire was giving evidence in the paper's libel fight with the MP.
Mr Galloway is suing the newspaper at the High Court over claims he took £375,000 from Saddam Hussein's regime.
But Mr Darbyshire said he was certain the documents used for the story were genuine and in the public interest.
Telegraph reporter David Blair says he uncovered the papers in the Iraqi foreign ministry in Baghdad.
Mr Darbyshire said they included a letter from Mr Galloway introducing his representative in Iraq for his Mariam Appeal, Fawaz Zureikat.
Another letter from Iraqi Deputy Prime Minister Tariq
Aziz told senior ministers about the MP's
forthcoming "work programme".
The work programme had not been found but Mr Darbyshire and his colleagues had agreed the documents could be the basis for an interesting story.
Mr Galloway had been a vocal opponent of the war and the documents had seemed to suggest a greater degree of cooperation between the MP and the Iraqi regime than previously known, he argued.
"It might also have offered some insight into the motives for his well-known
pro-Saddam stance," he said.
Mr Darbyshire said he became convinced the documents were genuine and that on the face of them there was a strong case for Mr Galloway to answer.
"It was therefore a tremendously important story," he told the court.
"I had no doubt that the public had the right to be told about the existence
of the documents and what they appeared to be saying, so long as we gave due
prominence to what Mr Galloway had to say about the documents, his dealings with
Saddam Hussein's regime and the nature of his relationship with Mr Zureikat."
He has also believed the documents should be reported as Mr Galloway was continuing to oppose the Iraq war, which was at a "volatile stage".
Mr Galloway has branded the story "outrageous" and says he has always opposed Saddam Hussein.
The Telegraph executive said the MP was wrong to claim he was "hated" by the newspaper and predicted the story would have been published by the Times or the Guardian.
"We wouldn't agree with everything Mr Galloway said but newspapers tend to
like political bruisers because they are colourful and provide copy," he said.
As he was cross-examined by Mr Galloway's QC, Richard Rampton, he denied there had been a "witch hunt" by the newspaper and said it had not gone looking for documents about the MP.
Mr Rampton suggested the Telegraph had engaged in a "massive exercise in politically motivated character assassination on
a grand scale".
That claim was branded "absolute claptrap" by Mr Darbyshire.
The judge, Mr Justice Eady, highlighted an editorial in the newspaper entitled "Saddam's little helper" and talking about treason and money coming out of Iraq's oil-for-food programme.
"Treason, on the face of it, sounds quite serious," he said, asking whether the references had been put to Mr Galloway before publication.
Mr Darbyshire could not remember a precedent for putting a leader article to somebody before publication.
Nor was it needed for the treason claim, "because of the caveats again -
if these allegations turn out to be true it's treason."
The judge, sitting without a jury, is due hear closing statements in the case on Friday. He is likely to reserve his judgement so it is published at a later date.