NEW DELHI: A twin suicide bombing claimed by Islamic State killed 70 people in a Shi'ite district of Baghdad on Sunday. The attack was the deadliest such attack in the Iraqi capital this year, and comes as the Islamic State launches an offensive on Baghdad’s western outskirts.

Sources said that suicide bombers on motorcycles blew themselves up in a crowded mobile phone market in Sadr City. 100 people were wounded in addition to those killed.

The Islamic State claimed responsibility in a statement circulated online. "Our swords will not cease to cut off the heads of the rejectionist polytheists, wherever they are," it said, using derogatory terms for Shi'ite Muslims.

The attack comes as Iraqi forces, backed by the United States-led coalition, make headway in their fight against the Islamic State. The Iraqi army was able to beat back the militants from Ramadi in December, with all eyes now trained on Mosul where the Iraqi government is mounting a fight. Further, Islamic State fighters also suffered a setback in Kirkuk province, as Kurdish fighters drove them out of the town of Hawija.

The success in Ramada was all the more significant as it was the first city recaptured by the Iraqi army without the help of militias. Ramadi is a mainly Sunni Arab city about 55 miles (90km) west of Baghdad. The sectarian nature of the city made the fight even more difficult, as the government decided not to use Shia peshmerga forces that had helped it recapture Tikrit for fear of increasing sectarian tensions.

The use of Shia militias in recapturing Sunni majority locations has been problematic as it has stoked sectarian tensions -- which the mainstream narrative believes contributed to the rise of the Islamic State in the first place.

The government, led by a Shi’ite Prime Minister, Haider al-Abadi, said Ramadi would be handed over to local police, a Sunni tribal force once it was secured as a measure meant to win over the community to the fight against Islamic State.

The attacks, however, symbolise that the fight is far from over, as Sunday’s death toll made it the worst attack on Baghdad this year. In January, on a single day, 51 people were killed in a spate of attacks in and around Baghdad. Islamic State claimed the attacks saying that they targeted “rejectionist” -- a derogatory term the group uses to describe Shia Muslims, and said that there was “worse to come.”

More recently, on Thursday, two Islamic State suicide bombers killed 15 people at a mosque in the capital.

On Sunday, suicide bombers and gunmen attacked Iraqi security forces in Abu Ghraib, seizing positions in a grain silo and a cemetery, and killing at least 17 members of the security forces, Reuters reported. Security officials blamed Islamic State, and a news agency that supports the group said it had launched a "wide attack" in Abu Ghraib, 25 km (15 miles) from the center of Baghdad and next to the international airport. Footage circulated online by the Amaq news agency appeared to show Islamic State fighters crouching behind dirt berms and launching the attack with automatic rifles, machine guns and rocket-propelled grenades. Reuters added that it could not verify the video's authenticity.

(Credit: The Wall Street Journal)

Prime Minister Haider al-Abadi said the attacks were in response to Islamic State's recent defeats: "This gang targeted civilians after it lost the initiative and its dregs fled the battlefield before our proud fighters," the Prime Minister posted on his official Facebook page.

Ali Ahmed, a senior fellow with the American University of Iraq’s Institute of Regional and International Studies, told The Wall Street Journal that Sunday’s attacks were an attempt by Islamic State to provoke Shiite reprisals against Sunnis ahead of the government’s planned offensives to retake remaining territory from the militancy.

“It is choosing this timing because it is suffering from setbacks on the battlefield in various parts of Iraq, and this is its way of reinvigorating its base,” Ali said. “The possible retribution attacks will be used by ISIS to discourage the population in Mosul and elsewhere in the Iraqi Sunni heartland from cooperating with government troops.”