A series of bombs has exploded at a campaign rally for a Shia group in Iraq's capital ahead of the country's parliamentary election, killing at least 37 people and wounding scores others, police said.

Friday’s explosions struck as some 10,000 people gathered at the Industrial Stadium in eastern Baghdad for a rally of the Asaib Ahl al-Haq group. The Shia group had planned to announce at the rally its candidates for Iraq's parliamentary election on Wednesday.

Qais al-Khazali, leader Asaib Ahl al-Haq, gave a brief address to his supporters before the blasts hit the rally [Reuters]

Police and medical officials said several of the wounded were in critical condition. They spoke on condition of anonymity as they were not authorised to release the information.

Followers of Asaib Ahl al-Haq carried out deadly attacks against US troops before their withdrawal from Iraq in 2011 and claimed responsibility for the 2007 kidnapping of a British contractor along with his four guards.

The group is backed by Iran and says it is sending fighters to Syria.

Its leader, Sheik Qais al-Khazali, spent years in US detention but was released after he was handed over to the Iraqi government. At the rally on Friday, he gave a brief address that challenged the Sunni fighters holding two cities in Anbar province.

Sectarian violence

Security guards jumped on Khazali and pushed him away from the stadium after the blasts.

The blasts highlight the sectarian violence that has plagued Iraq recently.

Last year, the death toll in the country climbed to its highest levels since the worst of the country's sectarian bloodletting between 2006 and 2008.

The UN said 8,868 people were killed in 2013, and more than 1,400 people were killed in the first two months of this year alone.

No one immediately claimed responsibility for the attack, though an al-Qaeda spin-off group known as the Islamic State of Iraq and the Levant uses similar tactics.

The group and other Sunni fighters frequently use car bombs and suicide attacks to target public areas and government buildings in their bid to undermine confidence in the Shiite-led government and target Shia groups.

More than 9,000 candidates are taking part in Wednesday's elections and will vie for 328 seats in parliament.

Parts of the Sunni-dominated Anbar province won't take part in the election due the clashes there between security forces and al-Qaeda-inspired fighters.

Source: Al Jazeera and agencies