Afghan government could fall to Taliban in 90 days, say US officials

Sarposa prison in Kandahar is latest site overrun by militants, with almost 1,000 prisoners released

US officials have warned that Afghanistan's government could fall in 90 days, with Kabul isolated in as little as a month, as the Taliban overran the central Sarposa prison in Kandahar, the country's second largest city, releasing almost 1000 prisoners.

The fall of Kandahar - sometimes called the capital of the south - would be a devastating blow for the Afghan government after a week in which the Taliban have swept up provincial capitals around the country in a lightning offensive.