President Barack Obama is calling on Americans to rekindle the spirit of unity that characterised the response to the 11 September 2001 attacks. “It can be a lasting virtue,” he said. “Not just on one day, but every day.”

The president made his appeal during his weekly radio and Internet address, just two weeks before the 10th anniversary of the al-Qaeda plot that turned commercial jetliners into deadly weapons in New York, Pennsylvania and northern Virginia.

Obama plans to observe the anniversary on 11 September with stops at Ground Zero in lower Manhattan, where the World Trade Centre towers fell; at Shanksville, Pennsylvania, where one of the commandeered planes crashed; and at the Pentagon, which was also hit by a hijacked jetliner.

But he cast his plea for good will against the backdrop of the economic challenges facing the United States today. Coming in the aftermath of bitter partisan fights over government spending and tough criticism of his administration by Republican presidential candidates, his remarks were an overt call for greater cooperation.

“Even the smallest act of service, the simplest act of kindness, is a way to honour those we lost, a way to reclaim that spirit of unity that followed 9/11,” he said.

He recalled the work of volunteers following the attacks, the blood donations and the food and clothing drives.

“We were united, and the outpouring of generosity and compassion reminded us that in times of challenge, we Americans move forward together, as one people,” he said.

These days, he said, the country is still fighting al-Qaeda, it is ending the war in Iraq, pulling back troops from Afghanistan and “emerging from the worst economic crisis in our lifetimes”.

“None of this will be easy,” he said. “And it can’t be the work of government alone. As we saw after 9/11, the strength of America has always been the character and compassion of our people.

“So as we mark this solemn anniversary, let’s summon that spirit once more. And let’s show that the sense of common purpose that we need in America doesn’t have to be a fleeting moment; it can be a lasting virtue – not just on one day, but every day.”