Militants from the Islamic State (IS) group carried out a mass killing of hundreds of Iraqi soldiers captured when the extremists overran a military base north of Baghdad in June, a leading international watchdog has said.

At least 27 people were killed in a series of bombings across Baghdad today, including three over a span of less than 10 minutes.

Iraqi forces backed by tanks and helicopter gunships are battling insurgents in Saddam Hussein’s home town of Tikrit, one of two major cities seized by Sunni militants during a rapid advance across the north earlier this month.

Rallying troops after an overnight stay at an air base, US Vice President Dick Cheney said today that as long as freedom is suppressed in the Middle East, the region will remain a place of “stagnation, resentment and violence ready for export.”