China's most politically sensitive trial in three decades has ended after about seven hours, the wife of ousted politician Bo Xilai did not contest charges of murdering the British businessman Neil Heywood.

A verdict will be delivered at a later date.

A court official's account of the closed-door hearing signals that Gu Kailai and a family aide are sure to be convicted in a case that has ended her husband's career and rocked China's leadership.

Gu's trial is seen by many Chinese people as part of a push against Bo, an ambitious populist who made powerful enemies as he campaigned to join the next generation of top central leaders.

Bo was formerly considered a contender for the inner sanctum of power, the party's Politburo Standing Committee, in a once-in-a-decade leadership transition that is currently underway.

Gu and her co-accused were charged with poisoning Neil Heywood, a family friend, last year.

The official said the court was told Zhang, the family aide, had put poison in a drink of water that Gu then gave to Heywood who was drunk at the time.

His body was found last November in a hotel in Chongqing, the city where Bo was the Communist Party chief.

Gu and Zhang face the death penalty if convicted, but many legal experts expect Gu to be convicted but only sentenced to a lengthy jail term.

Entry to the courtroom was restricted but two British diplomats were invited to be present because of the nationality of the victim.

As the trial took place, police dragged away two Bo supporters into an unmarked car after they had appeared outside the courthouse, singing patriotic songs that were the trademark of Bo's populist leadership style and condemning the trial as a sham.