The US government says it was given a "heads up" on the detention of the partner of a journalist who published information from US whistleblower Edward Snowden, but insists it did not request it.

Nigeria's militant Islamist leader Abubakar Shekau may have been killed by security forces during a shoot-out, an army spokesman says.

Amazon's US website goes offline for about half an hour, the latest high-profile internet firm to face such a problem in recent days.

The chief executive of the UK Independence Party leaves his post by "mutual agreement", a spokesman for the party confirms.