BAGHDAD, Iraq - Suicide bombers shattered a day of prayers at two Shiite mosques and at a religious procession today, killing at least 27 people and injuring dozens more on the eve of Shiite Islam's most important holiday, officials said.

The blasts recalled deadly explosions on the Ashoura holiday a year ago that killed 181 during the religious festival.

The first blast occurred in Baghdad's southern Dora neighborhood near the al-Khadimain mosque and killed at least 15, Police Capt. Falah al-Mahdawi said. Another 20 were injured.

A second blast caused by a suicide bomber occurred outside the Al Bayaa mosque in a predominantly Shiite neighborhood of western Baghdad, Lt. Col. Jalal Sabry of the local police station said. An official at Baghdad's al-Yarmuk hospital said at least 10 victims were brought there from that explosion.

In the third blast, another suicide bomber blew himself up near an Ashoura procession in the Shiite Ash Shulah district northwest of the city center, killing two and injuring five, police 1st Lt. Waed Hussein said.

There were no immediate claims of responsibility, but Iraqis blamed radical Sunni Muslim insurgents, who have staged car bombs, shooting attacks and kidnappings in efforts to destabilize the country's reconstruction and provoke a sectarian civil war between Shiites and Sunnis.

"Those infidel Wahhabis, those Osama bin Laden followers, they did this because they hate Shiites," said Sari Abdullah, a worshipper at the al-Khadimain mosque who was injured by shrapnel from the explosion. "They are afraid of us. They are not Muslims. They are infidels."

Before the explosions occurred, Shiite leader Abdel Aziz al-Hakim gave a sermon at a mosque in another Baghdad suburb and called on Iraqi Shiites to unite under the banner of the newly elected National Assembly. His United Iraqi Alliance won 48 percent of the vote and controlled a majority of seats in the 275-seat parliament.

"I address all Iraqis of all national, religious affiliations. I call upon them to unite to confront all conspiracies against Iraq," al-Hakim said. "I want to confirm to all that the Iraq we want is a secure Iraq, an Iraq in which all people without exception feel justice and equality. Yes, yes for unity."

Today's attacks during the Islamic holy month of Muharram came one day before Ashoura, the holiest day of the year for Shiites. Ashoura marks the death of Imam Hussein, the grandson of the prophet Muhammad, in a seventh-century battle for leadership of the Islamic world.

The explosions came as Iraq partially sealed its land borders as part of stepped up security on the eve of the holiday.

In the first explosion, a suicide bomber entered the vestibule of al-Khadimain mosque in Baghdad's Dora neighborhood while worshippers knelt in prayer before detonating his explosives, witness Hussein Rahim Qassim said. The blast killed 15 people, an official at Baghdad's al-Yarmuk Hospital said on condition of anonymity.

The mosque's imam used the minaret's loudspeakers to appeal for donations of blood, said 1st Lt. Ahmad Ali, who also said a suicide bomber was behind the blast.

Another bomb then ripped through the Al Bayaa mosque in a predominantly Shiite neighborhood in western Baghdad. Ten people were killed, the hospital official said.

Within the hour, a suicide bomber blew himself up as a procession of Shiites passed by, killing two and injuring eight, according to Iraqi police Lt. Waed Hussein.

During his sermon, al-Hakim insisted on pursuing former supporters of Saddam Hussein's Baath Party and removing them from power. The imam blamed them for the recent killings of three members of the Iran-backed Badr Brigades, the military wing of Iraq's largest opposition Shiite party, the Supreme Council for the Islamic Revolution in Iraq.