Iraq: 'Despicable attacks' raise sectarian fears

• Most of the victims are Shiite pilgrims
• The attacks were aimed at Shiite pilgrims trekking and driving to a shrine in Baghdad
• The shrine to al-Kadhim in Baghdad is one of Shiite Islam's holiest sites

Baghdad (CNN) -- The death toll from Wednesday's wave of attacks across Iraq rose to 93 and 312 people wounded, the Interior Ministry said Thursday, making it the deadliest day this year.

The attacks were mostly aimed at Shiite pilgrims trekking and driving to a shrine in Baghdad.

The scale of violence left some stunned.

"I am deeply shocked and utterly dismayed by the despicable attacks across Iraq today that have claimed the lives of scores of Iraqis, including many pilgrims, and have injured dozens more," said Martin Kobler, the U.N. secretary-general's special representative for Iraq.

Inside the mind of an Iraq combat vet

Open Mic: Iraqis' message to U.S.

"The scale of the violence is disturbing. I urgently appeal to the government to address the root causes of the violence and terrorism that are causing so much suffering and pain to the Iraqi people."

En route from across the country, including the Shiite heartland of southern Iraq, pilgrims have been headed to the Imam Kadhim shrine in the Kadhimiya neighborhood of Baghdad. The event culminates Saturday when the faithful commemorate the death of Imam Moussa al-Kadhim, one of 12 revered imams in Shiite Islam.

The violence sparks fears of a renewal of the fighting between Sunnis and Shiites in Iraq in the last decade, a longtime animosity intensified by the U.S. invasion of Iraq and the toppling of the Saddam Hussein regime.

Most people in Iraq are Shiites, but under Hussein, Sunnis held a great deal of power despite their minority status.

Shiites gained the upper hand politically after Hussein was overthrown by a U.S.-led invasion in 2003. Sunnis felt disenfranchised amid that political backdrop, and many backed insurgent actions against the government.

As a result, Sunni-Shiite violence exploded in the early 2000s.

One of the deadliest days of the year came on January 5 when at least 60 people were killed in attacks that again targeted Shiites on a pilgrimage.

But Wednesday's violence eclipses that day.

CNN's Joe Sterling contributed to this report.