Pakistan's only representative at the Sochi Winter Olympics is 16-year-old Muhammad Karim. He spoke to the BBC about how he got into skiing, and what the opportunity to take part means to him.

Can wearable sleep monitors give athletes a competitive edge? The BBC's Jane O'Brien reports.

Fifteen policemen go on trial in Brazil, accused of taking part in a 1992 massacre at the Carandiru prison in Sao Paulo that left 111 prisoners dead.

The city of Chicago is considering drastic measures that could cost up to $18bn (£11bn) to prevent Asian carp infesting North America's Great Lakes.

Iran and six world powers are to open the first round of talks in Vienna to seek a long-term agreement on Tehran's controversial nuclear programme.

Islamist militant group Ansar Bayt al-Maqdis says it bombed a tourist bus in Egypt's Sinai peninsula, killing three South Koreans and an Egyptian.

Fighting breaks out in the South Sudanese oil town of Malakal, officials say, the first major clashes since a ceasefire agreement in January.

A series of car bomb explosions in and around the Iraqi capital, Baghdad, has killed at least 33 people, officials say.