Barack Obama's former pastor, the Rev Jeremiah Wright, blasted news media he said had sensationalised his remarks in an often confrontational appearance at a reporters' club on Monday.

But the Chicago preacher stood by the fiery sermons that have dogged Obama's Democratic presidential campaign since they gained public attention in March.

"You cannot do terrorism on other people and not expect it to come back to you," Wright said at the National Press Club when asked about a speech in which he asserted the September 11 attacks were retaliation for US foreign policy.

Asked about another sermon in which he suggested the US Government created the Aids virus to kill black people, Wright also did not retreat.

"Based on what has happened to Africans in this country, I believe our government is capable of doing anything," he said.

Obama, who is battling fellow Democrat Hillary Clinton for the right to take on Republican John McCain in the November presidential election, joined Wright's Trinity United Church of Christ 20 years ago.

Obama told reporters at the airport in Wilmington, North Carolina that his former pastor is free to speak his mind but does not speak for his presidential campaign.

"I have said before and I repeat again that ... some of the comments that Rev Wright has made offend me and I understand why they have offended the American people."

Obama has distanced himself from Wright's remarks and denounced some of his views, which many voters have interpreted as anti-American.

"Those citizens who say that have never heard my sermons," Wright said. "I served six years in the military. Does that make me patriotic? How many years did Cheney serve?"

Vice President Dick Cheney, an architect of the Iraq war, received student deferments that kept him out of military service during the Vietnam War.

Asked about a remark - "God Bless America? No, God damn America" - that has been widely circulated online, Wright said he had been quoting an Iraqi official.

"God damns some practices, and there is no excuse for some of the things the government, not the American people, have done. That doesn't make me not like America, or unpatriotic," he said.

Wright, 66, said news coverage of his sermons showed a fundamental misunderstanding of the black religious tradition in America, which evolved over hundreds of years of slavery and repression.

"This is an attack on the black church," he said. "If you think I'm going to let you talk about my momma and her religious tradition, and my daddy and his religious tradition, you've got another think coming."

He said his church has a long history of political activism but also feeds, houses and educates thousands of needy people each year.

Wright was cheered enthusiastically by many black churchgoers in the audience, who often groaned in exasperation when the moderator asked questions submitted by journalists.

Wright, too, often challenged his questioners. He asked the moderator when she had last been to church and what her pastor had said there.

Others he dismissed as ignorant.

"You haven't heard the whole sermon? Well, that nullifies that question," he responded at one point.