Asked what would give him satisfaction, Berg, an anti-war activist and candidate for U.S. Congress, said, "The end of the war and getting rid of George Bush."

The United States said its aircraft killed Abu Musab al-Zarqawi, the insurgent leader who masterminded the death of hundreds in suicide bombings and was blamed for the videotaped beheading of Nick Berg, a U.S. contractor, and other captives.

"I don't think that Zarqawi is himself responsible for the killings of hundreds of thousands of people in Iraq," Berg said in a combative television interview with the U.S. Fox News network. "I think George Bush is.

"George Bush is the one that invaded this country, George Bush is the one that destabilized it so that Zarqawi could get in, so that Zarqawi had a need to get in, to defend his region of the country from American invaders."

Berg said Bush was to blame for the torture of Iraqi prisoners by U.S. soldiers at Abu Ghraib prison near Baghdad.

"Yeah, like George Bush didn't OK the torture and death and rape of people in the Abu Ghraib prison for which my son was killed in retaliation?" he told his Fox interviewers.

In a telephone interview with Reuters from his home in Wilmington, Delaware, the father said: "I have no sense of relief, just sadness that another human being had to die."

Berg, who is running as a Green Party candidate, has repeatedly blamed Bush and Defense Secretary Donald Rumsfeld for his 26-year-old son's death.

Nick Berg's videotaped beheading by hooded captors was posted on the Internet, and the father said he could understand what Zarqawi's family was going through.

"I have learned to forgive a long time ago, and I regret mostly that that will bring about another wave of revenge from his cohorts from al Qaeda," he told Fox.

Zarqawi's organization took responsibility for the execution of Nick Berg in May 2004. The video was published with a caption saying: "Abu Musab al-Zarqawi slaughtering an American."

When an Islamist Web site showed the video of a man severing Berg's head, the CIA said Zarqawi was probably the one wielding the knife. The father said he was not convinced.

"I have been lied to by my own government," he told Reuters on Thursday.