Iraq's main Sunni Arab political party is demanding an international investigation into allegations of torture at secret jails.
The Iraqi Islamic Party is accusing the Shiites of trying to suppress the Sunnis before next month's parliamentary elections.
Secretary-general Tariq al-Hashimi said the country's top Shiite cleric; Grand Ayatollah Ali al-Sistani should "condemn these acts."
Many Sunnis think agents from Iran are involved.
They suspect the Shiites of being allies of Iran.
Iraqi Prime Minister Ibrahim al-Jaafari confirmed Tuesday that more than 170 Interior Ministry prisoners were malnourished and possibly tortured at a Baghdad lockup.
A Pentagon spokesman says U.S. and Iraqi forces went into the Baghdad facility and "found things that concerned them."
Interior Ministry officials say there will be an investigation into the torture allegations.