A wave of bombings and other attacks in several Iraqi provinces including a number of locations in Baghdad that reportedly killed at least 55 people and wounded dozens during a major Shi’a religious festival has been condemned by Amnesty International.

At least 18 people were reportedly killed by several bombs across Baghdad as Shi’a pilgrims gathered to mark the anniversary of the death of the imam Moussa al-Kadhim, a great-grandson of the prophet Muhammad.

However, figures published by the Ministry of Interior point to a lower death toll, with at least 23 killed across the country.

“Deliberate attacks  on members of the general populationshow a complete disregard for the right to life and can never be justified,” said Hassiba Hadj Sahraoui, Amnesty International’s Deputy Director for the Middle East and North Africa.

“There needs to be a prompt, thorough and impartial investigation. Those found responsible must be brought to justice in proceedings that meet international standards of fairness, and without the imposition of the death penalty.”

In a separate attack on Wednesday in the mainly Shi’ite southern city of Hilla, two car bombs, including one detonated by a suicide bomber, exploded outside restaurants used by security forces, reportedly  killing 22 people and wounding 38.

No one has claimed responsibility for any of the attacks so far, which come amid a deepening political crisis in the country.

Violence in Iraq has increased considerably since the last US soldiers left the country in December 2011. In January 2012, at least 55 civilians were killed in suicide bombs and other attacks across the country. There has been a wave of attacks on the Shi’a community in recent days, including on Sunday when six people were killed in a mortar attack in a square filled with Shi’a pilgrims.