Iraq says former prisoners behind attacks

* Ministry official says prisoners behind spike in violence

* Amnesty law meant to foster peace among factions

* U.S. combat troops prepare to leave Iraq by Aug 2010

BAGHDAD, May 14 (Reuters) - The release of Iraqi prisoners from U.S. and Iraqi jails has contributed to a spike in violence in the country, an Interior Ministry official said on Thursday.

Iraq has attempted to foster peace among its feuding factions by releasing prisoners under an amnesty law.

But Deputy Interior Minister Adnan al-Asadi told reporters: "Some of them (attacks) are because of the release of detainees in American prisons or Iraqi prisons.

"The amnesty law included many dangerous prisoners, consequently there are efforts to (re) arrest some accused people and criminals," he added, referring to a 2008 Iraqi law that released some prisoners charged with lesser crimes.

Attacks in Iraq are still well below their 2006-2007 peak, but the recent surge comes as U.S. combat troops prepare to leave Iraq by the end of August 2010, followed by a full withdrawal by the end of 2011.

Prime Minister Nuri al-Maliki on Wednesday said "hasty" release of prisoners in U.S. military detention was one reason for increased attacks.

A series of bomb attacks ripped through Baghdad and other parts of Iraq in recent weeks, making April the deadliest month in Iraq for civilians since November. Asadi said former prisoners were behind three or four of ten recent blasts.

Under a deal signed with Baghdad that took effect this year, the U.S. military must release Iraqi prisoners if there is not enough evidence against them for a conviction in an Iraqi court.

Some 3,000 Iraqis had been released from U.S. prisons this year by the end of April, but U.S. officials said they were unlikely to be behind the spike in violence. About 18,600 were released in 2008, which saw dramatic falls in violence in Iraq.

The U.S. military runs rehabilitation programmes in its detention camps, where prisoners can take classes including English, sewing or computers, providing skills it hopes will steer detainees away from violence after they are released.

The violence may also affect Iraqi politicians' plans for parliamentary polls due early next year. Political accommodation between Iraq's majority Shi'ites, minority Sunnis and other groups is seen as key to stability after U.S. troops leave.

Thousands of prisoners who were not charged with major crimes have been released from Iraqi prisons following last year's passage of the amnesty law, meant to foster reconciliation between the mainly Sunni Arab prisoners and the Shi'ite-led government. (Writing by Mohammed Abbas: Editing by Janet Lawrence)