A bus carrying Pakistani pilgrims overturned in Iran, killing 28 passengers, Iranian state media report.

The crash happened on Tuesday night in the central Iranian province of Yazd and was due to a defective braking system, Reuters reported, citing a preliminary police investigation.

Another 23 passengers were injured – seven of them are in a critical condition, the province’s crisis management director told state TV.

The pilgrims were on their way to Iraq to commemorate a Shia saint who died in the 7th Century, according to the AP news agency.

Eleven women and 17 men are among those who died in the crash, according to the crisis management director.

Some two million Shia Muslim pilgrims are currently taking part in the annual pilgrimage, which spans about 80km (50 miles) from Najaf to Karbala in Iraq.

Iran is notorious for its poor traffic safety record, with some 20,000 deaths annually due to accidents.