Al Qaeda's affiliate in Iraq claimed responsibility for a wave of coordinated attacks that mainly targeted police forces in Shi'ite areas and killed at least 60 people across the country on Thursday.

In a statement seen on Islamist websites on Friday, the group said it carried out the attacks in revenge for what it called a torture and liquidation campaign that Sunni women and men are being subjected to in Baghdad's prisons and other areas.

Thursday's attacks hit at least 14 cities and towns across Iraq, highlighting the threat al Qaeda and other militant groups continue to pose to security forces after the withdrawal of U.S. troops in mid-December.

Thursday's violence, along with a suicide car bombing outside a Baghdad police academy the week before, broke weeks of relative calm as Shi'ite Prime Minister Nuri al-Maliki and Sunni politicians sought to resolve a political crisis that stoked sectarian tensions.

The U.S.-based SITE Intelligence Group said on Friday the Islamic State of Iraq, an umbrella group for al Qaeda-linked Sunni insurgents, announced it had struck Iraqi officials and military headquarters in a statement posted on Islamist websites on Thursday.

The operations came in a simultaneous way and on targets that had been observed and selected with precision, and they included security headquarters, military patrols and political, judicial and administrative leaders, the statement, dated February 23, said.

All thanks be to God (for) .... completely surprising the enemy in most of the country's provinces despite the size and scale of the attacks executed.

Many of Iraq's minority Sunnis, once dominant under former dictator Saddam Hussein, suspect Maliki is trying to grab more power from them for the benefit of Shi'ites, who are a majority.

In October Iraq arrested at least 240 former members of Saddam Hussein's Baath Party and former military officers, many of whom are believed to be Sunni, in a move some senior officials described as a plot to seize power after U.S. troops completed their withdrawal.

Officials said the arrests were made to foil a Baathist plot to launch sabotage attacks and topple Maliki's government.

A day after U.S. troops left the country, Maliki ordered the arrest of a Sunni vice president and sought to dismiss a senior Sunni deputy, moves that escalated sectarian tensions and which coincided with a wave of attacks against Shi'ite targets.

That violence and Thursday's attacks have revived fears of a return to the brutal sectarian warfare that killed tens of thousands of Iraqis in 2006 and 2007, especially as security forces continue to be the weakest link in establishing long-term stability in Iraq.

Late on Thursday and early on Friday, a number of attacks targeted police forces in Baquba, Iskandariya, Baghdad and Samarra. At least three members of the security forces were killed and seven wounded.

(Writing by Yara Bayoumy; editing by Francois Murphy and Philippa Fletcher)