Thieves have stolen a senior Tory politician's car and a laptop computer that was in it in a burglary at his home, sources said.
Shadow defence secretary Liam Fox was alone in his central London property when the burglary took place.
Sources denied that briefing papers for the leaders' television debate were among the items stolen.
Details of the break-in emerged on the day quarterly crime statistics for England and Wales were published by the Home Office.
Dr Fox had been due to outline the Tories' armed forces manifesto but the launch was cancelled at short notice.
A Scotland Yard spokesman said: "Police were called at 7.20am to an address in SE1 to reports of a burglary.
"Officers are currently in attendance and the burglary squad from Southwark are investigating."
There have been no arrests, the spokesman added.
A Conservative spokesman said: "I can confirm that Liam Fox's car was stolen last night and police are investigating."
According to sources, Mr Fox's wife Jesme was not in the property, in a gated community, because she is stuck in Hong Kong due to the travel chaos caused by the volcanic ash.