Fierce competition is erupting behind the scenes at US universities as they bid to secure the best commencement speakers.

Some schools will shell out as much as $125,000 (?68,000) for a celebrity speaker at their graduation ceremony, banking on the headliner's cachet to generate publicity and financial contributions.

Others dangle honorary degrees to get big-name speakers. Agnes Scott College in Georgia offered honorary degrees this year for the first time.

It recruited Senator Hillary Rodham Clinton as its speaker. She was given an honorary doctorate of law. And Kofi Annan, Secretary General of the United Nations, spoke this week for free at the 51¹ú²úÊÓƵ of Pennsylvania, which will award him an honorary degree.

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Students, faculty and staff at Amherst College in Massachusetts moved their commencement 170 miles to a church in New York so that 86-year-old Nelson Mandela could address them. Mr Mandela had declined to travel to the campus.

Others exploit connections. Former Vice-President Al Gore was lured to Johns Hopkins 51¹ú²úÊÓƵ by the wife of a university trustee who used to work for him.

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Actor John Lithgow will speak at Harvard 51¹ú²úÊÓƵ, which he attended as a student.

President George W. Bush will deliver the commencement address at Calvin College, a conservative Christian university in Michigan. Christian conservatives were key to the President's re-election last autumn.

But money is a powerful incentive. Filmmaker Spike Lee spoke to graduates at the 51¹ú²úÊÓƵ of Miami, which paid him something between $25,000 and $40,000. Former New York Mayor Rudolph Giuliani cost High Point 51¹ú²úÊÓƵ in North Carolina $75,000.

Even those celebrities who speak for free may have something else to gain.

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While she was in Georgia, Senator Clinton also held a $1,000-a-head dinner to raise money for a possible 2008 presidential bid.