Iraqi police say six people have been killed in the latest bomb
targeting Shi'ite pilgrims heading to Karbala for a religious festival.
They say saturday's car bombing in Baghdad also wounded at least nine people.
The pilgrims were making their way to Karbala, where hundreds of
thousands of people descended on the city for a festival marking the
birth of the Shi'ites' 12th and last Imam.
Iraqi authorities have tightened security in and around Karbala,
deploying more than 40-thousand police and soldiers during the festival.
About 30 Shi'ite pilgrims have been killed and dozens more wounded in attacks since Thursday.
Meanwhile, a U.S. military official says a branch of the Iranian Revolutionary Guards (Quds Force) and the Lebanese-based militant group Hezbollah are training Iraqi assassination teams in Iran.
He said they plan to target Iraqi officials, as well as U.S. and Iraqi troops.
The U.S. official, who requested anonymity, told Western news agencies
the Shi'ite "special groups" are being trained in the Iranian cities of
Qom, Tehran, Mashad and Ahvaz.
U.S. and Iraqi officials have accused Iran of arming Shi'ite militias
in Iraq. Iran denies supporting the insurgents and says the U.S.
military presence in Iraq is to blame for violence in the country.