ONDON, July 20 — The BBC said today that Dr. David Kelly, the British weapons expert who committed suicide last week, was the source for a report on doctoring intelligence files that led to a battle between the broadcaster and the government of Prime Minister Tony Blair.

The announcement by the BBC's director of news, Richard Sambrook, cast doubt on the network's credibility, because Dr. Kelly had told a parliamentary committee two days before his death that he had not provided the report's central contention — that the government had "sexed up" a government intelligence dossier by incorporating a claim that Saddam Hussein had chemical and biological weapons that could be deployed in 45 minutes.

The announcement further undermined the authority of the hotly contested report in that Dr. Kelly, 59, a former United Nations weapons inspector in Iraq and an adviser to the Ministry of Defense, was not a senior intelligence official involved in preparing the dossier, as the network had called its anonymous source.

The original report, broadcast on May 29, was particularly damaging to the government, which is fighting charges that it manipulated intelligence information to justify an unpopular war.

At the time, government officials vehemently denied the report, pressed the network for its source and repeatedly demanded a retraction and an apology. The BBC said it stood behind its reporting and demanded its own apology for the government's assertion that the broadcaster's news programming followed "an agenda against the war."

Dr. Kelly became involved in the dispute after telling his Defense Ministry managers that he had met with the BBC correspondent a week before the report was broadcast. His name was then leaked to newspapers, and he was brought before a House of Commons foreign affairs committee, which subjected him last Tuesday to a round of bruising questions and name-calling.

His family and friends have speculated that the bullying treatment overwhelmed the scientist, a soft-spoken man accustomed to working behind the scenes. In one e-mail message he sent hours before his death, he said that if things returned to normal, he would return to Baghdad by the end of the month. In another, sent to a reporter for The New York Times, Judith Miller, he discussed how his testimony had gone: "I will wait until the end of the week before judging — many dark actors playing games."

The police found Dr. Kelly's body on Friday in a wooded area five miles from his Oxfordshire home, his left wrist slashed and a package of painkillers nearby.

Mr. Blair has called for an immediate judicial inquiry into the suicide. Today, during a visit to South Korea, he said that he himself would testify.

For the BBC, the publicly financed network that sees itself as the world leader in balanced broadcast reporting and analysis, the highly charged case comes at an awkward time. The corporation was already under attack from critics who said it had not been impartial in its coverage of the war in Iraq and the conflict in the Middle East.

In addition to its continuing fight with the government at home, it is derided by right-wing commentators in the United States as "the Baghdad Broadcasting Corporation," and in Israel its correspondents have been officially shunned by the government of Ariel Sharon.

In an appearance before a committee of Parliament last week to discuss the network's annual report, BBC chiefs faced charges of partiality. One Labor member of the panel, Rosemary McKenna, said the network had ceased to "differentiate between straightforward news and editorial comment."

Gavyn Davies, the corporation's chairman, said he was disturbed by the spate of allegations, and he assured the lawmakers, "We are going to look further at whether we can ensure audience perceptions of impartiality, something we already do, but we want to do more."

Mr. Davies conceded that there were "some individual errors along the way," but said that research showed the BBC to be the most trusted information source in Britain.

BBC audience figures in the United States are rising, but BBC news correspondents are more aggressive and contrarian in their interviewing techniques than their American counterparts, a characteristic that can expose them to charges of taking sides among people who are accustomed to the media taking a less hectoring approach to public figures. BBC officials have responded to the criticism about their war coverage by saying they are appealing to an international audience that demands a perspective from both sides.

Israel took its action against the BBC after the network broadcast a documentary in the spring about the secretiveness of the country's nuclear program. "It was a propaganda film of the very lowest level with a minimum of journalistic ethics or standards," said Gideon Meir, the Israeli Foreign Ministry's deputy director general for media and public affairs. "It was a clear attempt to show Israel as belonging to the world of dark dictatorships."

Interviewed by telephone from Jerusalem, Mr. Meir said the program was the "final straw in a campaign the BBC has been waging for the past three years bashing Israel and its government." As a result, he said, "We are not cooperating with the BBC, we don't give them any talking heads, we don't brief them and we don't invite them to press conferences."

The Israelis brought their attitude with them to the corporation's headquarters city last week. When the visiting prime minister, Mr. Sharon, held a news media breakfast in London, the BBC was barred from attending.