A woman with a one-year-old child led the US Secret Service and police on a harrowing car chase through Washington DC, attempting to penetrate the security barriers at the White House and the Capitol before she was shot to death, police said. The child survived.

Rock star Bono met US presidential candidate Barak Obama on Tuesday to discuss foreign assistance to anti-poverty and global health causes.

A suspicious letter was found today in the Washington office of Senate Majority Leader Tom Daschle, but police said an initial test on a powdery substance contained inside was negative.

Tens of thousands of letters mailed around the US could have picked up trace amounts of anthrax while passing through a contaminated postal centre, the nation’s top anthrax investigator has said.