BAGHDAD, Aug. 11 -- The Islamic State (IS) militant group on Tuesday claimed the responsibility for the two suicide car bomb attacks in Iraq's eastern province of Diyala, the group said in an online statement.

It said that Abdullah al-Ansari, an Iraqi suicide bomber, blew up his booby-trapped car on Monday amid a crowd of Shiite people in the village of Huwaider near the provincial capital city of Baquba, some 65 km northeast of Baghdad, killing and wounding more than 100 "rejectionists," as the extremist Sunni group refers to the Shiite Muslims.

Late on Monday, a massive explosion occurred at a busy marketplace in Huwaider village when a suicide bomber detonated a truck carrying nearly three tons of explosives covered with vegetables, leaving more than 53 people killed and more than 70 wounded, a provincial security source told Xinhua, citing latest reports.

Earlier, the source put the toll at 35 killed and some 65 wounded, 20 were in critical conditions, by the huge blast which also destroyed 20 shops and many stalls at the market along with damaging several nearby cars and buildings.

Also in the province, another suicide bomber rammed his explosive-laden car into a security checkpoint and blew it up at the entrance of the town of Kanaan, some 20 km northeast of Baquba, leaving five policemen, two government-backed Sahwa paramilitary group members and a civilian dead, the source said.

Four civilians who were passing the checkpoint were also wounded in the blast, the source added.

The Sahwa groups, or the Awakening Councils, consists of armed groups including some powerful anti-U.S. Sunni insurgent groups, who turned their rifles against the al-Qaida network after the latter exercised indiscriminate killings against both Shiite and Sunni Muslim communities.

Diyala province, which stretches from the east edges of Baghdad to the Iranian border, has long been the stronghold of al-Qaida militant groups and a hotbed of insurgency and sectarian violence after the U.S.-led invasion in 2003.

The security situation in Iraq has drastically deteriorated since June 2014, when bloody clashes broke out between security forces and Islamic State militants.