The United States pledged one billion dollars to help stabilise Pakistan on Friday, at the start of a donors conference that the World Bank hopes will raise up to six billion dollars. Saudi Arabia also pledged up to 700 million dollars for Pakistan. Almost 30 countries met in Tokyo to pledge aid for Pakistan, which shares a long border with Afghanistan and is seen by US President Barack Obama as being at the forefront of the battle against Al-Qaeda and Taliban. President Asif Ali Zardari said at the opening of the conference that "we are ready to fight" extremism, even though "there is a bomb blast every third day" in his country. "In spite of the fact that I lost the mother of my children, I have taken up this challenge," President Zardari said. "It does not end on my border. If we lose, you lose. If we are losers, the world is a loser." Japan's Prime Minister Taro Aso, who on Thursday pledged up to one billion dollars for Pakistan, said that "seven and a half years have passed since the 9/11 terrorist attacks, and the world is still facing the threat of terrorism. "Even now, tragedies are being repeated in Islamabad, Lahore, Mumbai and Kabul. Terrorism is posing a threat to the international community, and we cannot help but acknowledge that efforts to eradicate terrorism are now at a crucial stage." "Pakistan has played a vitally important role in efforts of the international community to counter terrorism and extremism," he said. The United States also pledged one billion dollars over two years. US regional envoy Richard Holbrooke "announced the United States' intent to provide support, totaling one billion dollars over a two-year period" in the closed-door meeting, said State Department acting spokesman Robert Wood. Holbrooke called it "a down payment on President Obama's commitment" to support a bill to pump 1.5 billion dollars a year into Pakistan for at least five years to build schools and infrastructure that can nurture democracy. The World Bank has said it expects total loan and grant aid pledges of four billion to six billion dollars from the 27 countries and 16 organisations attending the one-day conference and a "Friends of Pakistan" meeting.