Washington, Sep 10 (DPA) Edward Kennedy, who for decades championed health care reform in the US Senate until his death last month, has spoken out one last time on the issue that was closest to his heart.

In a speech Wednesday to a joint session of Congress, President Barack Obama revealed that Kennedy wrote him a final letter in May - after being informed that his brain cancer was terminal - and instructed it to be delivered only after his death.

In the letter, released by the White House, Kennedy calls comprehensive health reform 'the great unfinished business of our society'. He said the 'prospect of victory' in Congress after so many years had helped keep him going in the final months of his life.

'What we face is above all a moral issue,' wrote Kennedy, who died August 26 at age 77. 'At stake are not just the details of policy but fundamental principles of social justice and the character of our country.'

Obama read an excerpt of the letter during his speech to Congress, in which he called on legislators to end their bickering of the last few months and pass major health reforms by the end of the year.

He said that Kennedy's own passion for health reform was borne out of personal experience: He lost two children to cancer.