The Wall Street Journal says a British businessman who was killed in China had been providing information to the British secret service.
The paper reported on Tuesday that Neil Heywood had been communicating with an MI6 officer about Bo Xilai, the former Communist Party chief of Chongqing, for at least a year before he died in November 2011.
In April, Foreign Secretary William Hague said Mr Heywood was not a government employee "in any capacity".
The case is at the heart of China's biggest political scandal in decades.
The death of Mr Heywood brought down Mr Bo, a high-flier who was once tipped for top office.
Mr Bo's wife, Gu Kailai, was sentenced to prison in August for the murder of Mr Heywood at a Chongqing hotel. His former police chief, Wang Lijun, wasd also jailed in connection with the scandal.
Mr Bo was expelled from parliament in September, stripping him of immunity from prosecution. He is expected to go on trial in the future.
Mr Heywood, 41, had lived in China from the early 1990s, where he learned fluent Mandarin.
The nature of his association with Mr Bo and his wife Gu is not clear, but he has been described in some reports as a financial middleman. State media say Gu Kailai killed him over a business deal that went sour.