An al-Qaida group has claimed responsibility for recent bombings in the Iraqi city of Tikrit that left at least 34 people dead.

The militant group posted a statement on a jihadist website on Wednesday saying it was behind two bombings in the city north of Baghdad on Friday and a third attack on Monday.

Iraqi officials said at least 21 people were killed in apparently coordinated bombings on Friday. Most of the victims were worshippers who were coming out of a Sunni mosque when a bomb exploded. Several hours later, a suicide bomber detonated explosives at Tikrit's main hospital, where many of the victims of the first blast had been taken.

On Monday, a suicide bomber detonated a car outside a government compound in Tikrit, killing at least 13 people including an Iraqi army colonel.

Five U.S. servicemen were killed later in the day in a Baghdad attack but the al-Qaida statement did not mention the incident.

The attacks have come as the U.S. winds down its military presence in Iraq, with a goal of withdrawing by the end of the year.

In April, Prime Minister Nouri al-Maliki said Baghdad did not need help maintaining internal security but might need help with external security. However, Iraq has not formally asked the U.S. to extend its mission.