By John Ruwitch

HEFEI, China (Reuters) - A Chinese court on Monday sentenced Gu Kailai, wife of ousted politician Bo Xilai, to death with a two-year reprieve for murdering a British businessman, two witnesses to the closed-door hearing said, in a scandal that has shaken China's leadership transition.

The sentence means that Gu is likely to face life in jail, provided she does not commit offences in the next two years.

At a trial on August 9, Gu admitted to poisoning the businessman, Neil Heywood, in November, and alleged that a business dispute between them led him to threaten her son, Bo Guagua, according to official accounts published by state media.

"We respect the court's decision," He Zhengsheng, a lawyer for the Heywood family, told reporters. He and another witness to the hearing, which was barred to all but a few journalists from official Chinese media, revealed the verdict to throngs of reporters waiting outside the courtroom.

They both also said Zhang Xiaojun, an aide to the Bo household, was sentenced to nine years in prison for acting as an accomplice to the poisoning of Heywood.

Gu's sentencing could be a prelude to formal punishment of Bo Xilai, a brashly ambitious politician under investigation for alleged violations of party discipline -- an accusation that covers corruption, abuse of power and other misdeeds. After the party leadership decides on those allegations, Bo Xilai could also face criminal charges related to the murder case.

Bo's hopes for securing a spot in China's next top leadership unraveled after his former police chief, Wang Lijun, fled to a U.S. consulate in early February for about 24 hours and exposed the murder allegations.

Bo, the son of a revolutionary, ran the southwestern city of Chongqing where Heywood was killed. Bo was seen as competing for a place in the Politburo Standing Committee, the body at the pinnacle of power in China, at a once-in-a-decade leadership transition later this year.

His downfall has stirred more division than that of any other leader for over two decades. To leftist supporters, Bo was a charismatic rallying figure for efforts to reimpose party control over dizzying, unequal market-led growth.

But he made powerful enemies among those who saw him as an opportunist who wanted to impose his policies on the country.

Bo was sacked as Chongqing boss in March and Gu was publicly accused of the murder in April, when Bo was suspended from the Politburo, a 25-member elite council that ranks below the Standing Committee. He has yet to be expelled from that council.

Four Chinese policemen have also admitted to charges that they sought to protect Gu from investigation -- a development that could also prove dangerous for Bo.

Police sources in Chongqing have said Bo tried to shut down the investigation into his wife after being told she was a suspect. Bo has not been seen in public since March, when he gave a combative defense of his policies and family at a news conference during China's annual parliament session.

(Additional reporting and writing by Chris Buckley; Editing by Tait and Mark Bendeich)