Dozens gathered at Baghdad's biggest Sunni mosque on Monday for the funeral of one of at least 28 people, including a lawmaker, killed in a suicide blast that has been blamed on Al-Qaeda.

The attack, the deadliest in Iraq in two weeks, came just days before the conclusion of the holy Muslim fasting month of Ramadan and the Eid al-Fitr festival that marks its end, and left elderly men, children and mosque officials among the casualties.

Torn off pieces of flesh still littered the Umm al-Qura mosque's main hall on Monday morning, hours after the attack, and trails of blood ran from the prayer area to the steps outside, indicating where the wounded were carried.

Stained glass windows were shattered and marble tiling on pillar walls was broken off, while blood-soaked blankets used to carry the wounded were scattered across the floor.

Outside the building, about 40 men gathered in a garden to pray over the body of Abdelrazzaq Mohsen al-Samarrai, a staff member of the Sunni Endowment, which is responsible for Sunni Muslim religious sites across Iraq and is based at the blue-domed mosque in west Baghdad.

His body, which was placed in an Iraqi flag-draped coffin, was then taken for burial. Other victims were being buried elsewhere on Monday.

An interior ministry official said 28 people were killed and 37 wounded in Sunday evening's attack, among them Khaled al-Fahdawi, an MP from western Anbar province allied with the Sunni-backed Iraqiya bloc.

A defence ministry official on Monday put the toll at 30 dead and 34 wounded.

Fahdawi, who previously survived an assassination attempt in 2005, was buried in his native Ramadi, capital of Anbar, on Monday morning, an official from the Sunni Endowment in the province said.

According to mosque chief Ahmed Abdulghafur Samarrai, the suicide bomber walked up to a crowd, covered in bandages, as he was giving a speech and detonated his explosives.

"He put bombs along his arms and he was also wearing an explosive belt," said the mosque chief, who is known for his sermons against violent extremism.

"Nobody imagined he was carrying bombs."

He said the attacker had been attending the mosque for several days with the bandages, becoming familiar with the complex's security guards, indicating the attack was planned in advance.

Samarrai told reporters inside the mosque's main hall: "There is no justification for this -- they attacked a mosque, old people and children. I saw legs and hands on the floor because of these killers."

"Do not describe them as Shiite or Sunni or Iraqis -- they are terrorists and terrorists have no religion."

Samarrai is one of the founders of the Sahwa, or Awakening, movement in the mostly Sunni north Baghdad neighbourhood of Adhamiyah.

The Sahwa are comprised of Sunni tribesmen who joined forces with the US military against Al-Qaeda from late 2006, helping turn the tide of the insurgency.

As a result, Sahwa fighters are despised by Al-Qaeda insurgents, and Samarrai has received several threats against his life.

The suicide blast was quickly condemned by Prime Minister Nuri al-Maliki and parliament speaker Osama al-Nujaifi.

Earlier on Monday, Baghdad security spokesman Major General Qassim Atta pointed the finger at Al-Qaeda, saying he was "100 percent certain" that the militant group was behind the attack.

The bomber "blew himself up in the middle of the people in the mosque to try to get the maximum number of casualties," he told AFP.

The death toll from the attack was the highest since August 15, when twin blasts in the southern city of Kut, also blamed on Al-Qaeda, killed 40 people.

In addition to the Umm al-Qura attack, bomb and gun attacks around Iraq on Sunday killed seven other people, among them three policemen, and left 26 others wounded, according to security officials.

Meanwhile, attacks on Monday in Baghdad, Ramadi, the central city of Baquba, and the main northern city of Mosul killed four policemen, a soldier and a Sahwa fighter and wounded 21 other people, security officials said.

The violence comes after Al-Qaeda's front group in Iraq threatened a campaign of 100 attacks, starting in mid-August, to avenge the death of Osama bin Laden in a US special forces raid in Pakistan in May.