Gordon Brown, Ban Ki-moon and Germany's Foreign Minister Guido Westerwelle were among those offering their public support for Hamid Karzai's victory on Monday.

French president Nicolas Sarkozy also assured Hamid Karzai of France's "full backing" as he congratulated the Afghan leader on his re-election.

"You have managed since the first round to get the most support from the Afghan people," Sarkozy said in a letter released by his office.

The president also hailed opposition leader Abdullah Abdullah's decision to pull out of the second round of the election as a "dignified retreat".

Obama applies pressure

US President Barack Obama's expression of support was more cautious. Speaking to Karzai on Monday, Obama urged Karzai to take a tougher stance on the country's endemic corruption: "I emphasized that this has to be a point in time in which we write a new chapter based on improved governance, a much more serious effort to eradicate corruption."

The US president, who is currently mulling whether to send thousands more troops to Afghanistan, put some pressure on Karzai to instigate joint efforts to accelerate the training of Afghan security forces.

Karzai "assured me that he understood the importance of this moment, but the truth is not going to be in words, it's going to be in deeds," Obama said.

Earlier on Monday, Afghanistan's Independent Election Commission (IEC) cancelled the upcoming presidential run-off and declared the incumbent candidate the winner.

Westerwelle gave Karzai a cautious congratulations, calling on him to become "the president of all Afghans". "We are fully on the side of the Afghan people," he assured reporters in a statement.

The British prime minister Gordon Brown also called Karzai to congratulate him, according to a spokesman.

"They discussed the importance of the president moving quickly to set out a unifying program for the future of Afghanistan," he said.

Win followed opposition pull-out

"Although the process was messy, I'm pleased to say that the final outcome was determined in accordance with Afghan law," Obama said.

The IEC's announcement came a day after former Foreign Minister Abdullah Abdullah pulled out of the presidential race, citing fears of a repeat of the fraud which marred the first round of voting in August.

"The Independent Election Commission declares the esteemed Hamid Karzai as the president ... because he was the winner of the first round and the only candidate in the second round," the commission's chief Azizullah Ludin told a news conference in Kabul.

UN welcomed the result

Monday's announcement coincided with a visit to Kabul by United Nations Chief Ban Ki-moon, who was the first to start off the chorus of well-wishers.

"I welcome today's decision by Afghanistan's Independent Election Commission to forego a run-off vote and to declare Hamid Karzai as the winner of the 2009 presidential elections," Ban said in a statement. "I congratulate President Karzai."

Hopes for compromise are dashed

Western diplomats had expressed concerns about staging a no-contest second-round election. Yet the outcome is unlikely to improve perceptions of Karzai's claim to legitimacy.

At the weekend, Karzai ruled out any form of power-sharing arrangement with Abdullah, dashing hopes of a compromise.

Abdullah had sought a raft of changes for the second-round vote, including the replacement of the head of the election commission. He chose to boycott the poll when his demands were rejected.

An investigation of the first round of voting found significant incidents of fraud had favored Karzai.

nw/sjt/Reuters/AFP/dpa/AP
Editor: Nancy Isenson