DIWANIYA, Iraq: A car bomb blast in a busy market in the southern Iraqi city of Diwaniya killed at least 25 people and wounded 50 others on Tuesday, police and a provincial council official said.

Earlier in the day, two roadside bombs targeting Shia pilgrims killed four people and wounded 21 near the central Iraqi city of Kerbala, hospital and police sources said.

In Diwaniya, 150 kilometres south of Baghdad, police announced a partial curfew and closed all entrances to the city.

The bombing took place near a Shia mosque where pilgrims gather on their way to Kerbala to celebrate the birthday of one of the most important imams — al-Mahdi — this week.

Attacks have increased in Iraq in recent weeks, raising fears that the country may slip back into widespread violence between Iraqi Sunni and Shia Muslims.

Last month at least 237 people were killed and 603 wounded mainly in bomb attacks, according to a Reuters tally, making June one of the bloodiest months in Iraq since US troops withdrew at the end of last year.

The deadliest attack occurred on June 13 when bombers targeting Shia pilgrims killed more than 70 people.