President Bush and British Prime Minister Tony Blair, who forged a close and complicated relationship over Iraq, agreed yesterday to increase financial assistance to developing African nations suffering from famine, AIDS and war. But the two leaders parted ways over how much money rich nations should provide to Africa and how they should ease global warming.

In their first visit together at the White House since winning reelection in campaigns dominated by Iraq and U.S. foreign policy, Bush and Blair trumpeted a new U.S. plan to spend $674 million more on famine relief and said a deal to erase millions of dollars owed by poor African nations is imminent. "Helping those who suffer and preventing the senseless death of millions of people in Africa is a central commitment of my administration's foreign policy," Bush told reporters.

Bush, however, refused to endorse Blair's more ambitious plan to double aid from rich nations to $25 billion each year and $50 billion annually starting in 2015. Instead, Bush promised more U.S. money and a deal on debt relief at next month's economic summit of the world's seven wealthiest nations and Russia, known as the Group of Eight (G-8), which Blair will host in Scotland. "We know there's a lot more to do," Blair said.

In a news conference that highlighted their complex alliance, Blair defended Bush over the "Downing Street memo," in which a top British official alleged in 2002 that the United States was manipulating intelligence to justify a military invasion of Iraq. The memo surfaced in the British media last month. "The facts were not being fixed in any shape or form at all," Blair said.

This was neither the first time Blair has rushed to Bush's defense on Iraq nor the only time the president did not reciprocate by providing the prime minister complete cover back home.

Blair's unwavering support for toppling Saddam Hussein proved instrumental in Bush's war planning. The prime minister provided thousands of troops, more than any other nation beyond the United States, and, perhaps more important, has offered a passionate intellectual and emotional defense of the war and efforts to create a democracy in Iraq.

The friendship almost cost Blair an unprecedented third term this year. The war remains very unpopular in Britain and a source of controversy and distraction for Blair's ruling Labor Party, which sustained heavy losses in the parliamentary elections. The British tabloids frequently lampoon the prime minister as Bush's "poodle" who gets little in return for the support Britain gives to the United States.

While sensitive to Blair's domestic problems, Bush often stops short of meeting the prime minister's political needs. When the two leaders met in April 2004, for instance, Bush praised Blair's support for the Iraq war but broke with the prime minister over the Middle East peace process, including the disposition of Israeli settlements in the West Bank. Many Britons saw Bush's position as a setback for Blair. Yesterday, both said they were committed to negotiating a peace deal that would create a Palestinian state.

This time, the White House leaked word of Bush's plan to announce increased aid to Africa the night before Blair arrived as way to divert attention away from the president's refusal to back Blair's more ambitious plan to dramatically increase global financial assistance to Africa. But the prime minister still made clear that he would have liked more.

The plight of Africans is taking center stage in international politics, as Blair travels the world asking rich nations to double aid; U2 and other bands plan a summer music tour highlighting AIDS and famine epidemics; and atrocities in Sudan command the attention of lawmakers, Christian activists close to the White House and the news media.

Bush is often criticized for not doing enough -- both to stop what he calls a genocide in Sudan and provide more money to supply medication and other assistance to people with AIDS and food for the needy. The Bush administration has tripled aid to Africa to $3.2 billion in 2004 and promised several billion more annually through the "Millennium Challenge" account, though that money has yet to be delivered. The president has also pledged almost $3 billion in annual AIDS relief, most of which will go to Africa.

The new $674 million commitment, which comes from money already approved by Congress for humanitarian relief, would mainly provide food to Ethiopia, Eritrea and a few other African nations threatened by famine. The White House said this money should provide food for 14 million people. Several advocacy groups said the amount of money is insufficient unless it is coupled with debt relief and additional financial assistance.

"I see we've got a fantastic opportunity, presuming that the countries in Africa make the right decisions. Nobody wants to give money to a country that's corrupt, where leaders take money and put it in their pocket," Bush said.

On global warming, Bush and Blair did not appear to make much progress. Bush has long opposed the 1997 Kyoto treaty that the United States refused to ratify. Blair, who plans to make the issue a key topic at the G-8 summit, wants world leaders to agree on the science of climate change and to lead an immediate worldwide effort to find solutions. "I think everyone knows there are different perspectives on this issue," he said.

Climate change was a key topic of a British Embassy breakfast Blair held for a bipartisan group of senators yesterday, with some Democrats urging him to lobby Bush more forcefully on the matter. Toward the end of the hour-long meeting, Sen. Thomas R. Carper (D-Del.) told Blair he had the best chance of persuading the president to embrace mandatory carbon dioxide emission cuts. "More than anyone sitting around this breakfast table, our president owes you a great deal," Carper told him. "I would not be shy about reminding him of that fact." If he did, it did not appear to work.

Bush, who has challenged studies suggesting man-made pollutants are causing Earth's temperatures to rise, said: "In terms of climate change, I've always said it's a serious long-term issue that needs to be dealt with."

Staff writer Juliet Eilperin contributed to this report.

British Prime Minister Tony Blair would like to erase all of Africa's international debt and also double aid from wealthy nations to $25 billion annually at first.