* One of the deadliest attacks this year
* Insurgents exploiting political tensions
* U.S. ending combat operations this month (updates with White House comment)
By Waleed Ibrahim and Ahmed Rasheed
BAGHDAD, Aug 17 (Reuters) - At least 57 recruits and soldiers were killed and 123 wounded when a suicide bomber blew himself up at an army recruitment centre in Baghdad on Tuesday, two weeks before the end of the U.S. combat mission in Iraq.
The blast, which tore through a line of recruits, was one of the bloodiest this year and occurred as suspected insurgents also launched an assassination campaign against judges in the Iraqi capital and a volatile province north of Baghdad.
The bloodshed added to tensions that have simmered following an inconclusive election more than five months ago that has yet to produce a new government.
Insurgents have been targeting Iraqi police and soldiers as they prepare to take full responsibility for security on Sept. 1, when the United States ends a 7-1/2 year combat mission.
U.S. troop numbers will be reduced to 50,000 for a training mission before a full withdrawal planned for next year.
"We were lined in a long queue. There were also officers and soldiers. Suddenly an explosion happened. Thank God only my hand was injured," recruit Saleh Aziz told Reuters Television while doctors in al-Karkh hospital treated his wounds.
A total of 57 people died and 123 were wounded in the attack on an army base near Baghdad’s central Maidan square, the media office of the Health Ministry said. One Defence Ministry source said the death toll could be as high as 61.
The White House said President Barack Obama condemned the attacks, but the U.S. withdrawal timetable had not changed.
"Our combat mission ends at the end of the month, but we will still have troops there who are helping to support (Iraqi forces) as necessary," spokesman Bill Burton told reporters on Air Force One.
The site of the attack used to be the Defence Ministry under Saddam Hussein, turned into an army recruitment centre and military base after the 2003 U.S.-led invasion.
One army source who declined to be identified said there might have been two suicide bombers, a hallmark of Sunni Islamist al Qaeda and its local affiliates.
"They (the recruits) were gathering in large numbers. They let in 250 recruits at a time," the source said.
In Baghdad and Diyala province, meanwhile, insurgents attacked eight judges with bombs and silenced weapons, killing two of them, a source in the Justice Ministry said.
"These attacks are well orchestrated," the source said. "They are targeting the entire judicial system of the country."
The bloodshed was the latest attack since the March 7 election produced no outright winner and pitted a Sunni-backed, cross-sectarian alliance against the country’s major Shi’ite-led factions.
While overall violence in Iraq has fallen sharply since the height in 2006-07 of the sectarian slaughter between majority Shi’ites and once dominant Sunnis, a stubborn insurgency remains capable of carrying out large scale attacks.
On Aug. 7, around 45 people were killed when explosions struck a market in the southern oil hub of Basra, and 39 were killed on July 18 on Baghdad’s southwestern outskirts when a suicide bomber attacked government-backed Sunni militia.
On May 10, around 125 people were killed nationwide in a wave of assaults by al Qaeda-linked militants who security officials said were trying to prove they remained a potent force despite the deaths of many of their leaders earlier this year.
Officials say the insurgents are now trying to exploit political tension stirred up by unsuccessful coalition talks between Shi’ite political factions and the Sunni-backed Iraqiya alliance, which won a narrow victory in March.
Hopes of a possible solution to the stalemate were dashed on Monday when Iraqiya, headed by former premier Iyad Allawi, broke off talks with Prime Minister Nuri al-Maliki.
The attackers also want to undermine faith in the Iraqi security forces as U.S. troops depart.
Baghdad security spokesman Major General Qassim al-Moussawi said half of the suicide bomber’s body had been recovered at the army recruitment centre and blamed the attack on al Qaeda.
"His features suggest he isn’t Iraqi. We are conducting an investigation but the fingerprints are obvious in this explosion," Moussawi said. (Additional reporting by Patricia Zengerle, Aseel Kami and Baghdad bureau; Writing by Michael Christie and Ulf Laessing; Editing by Alison Williams and Cynthia Osterman)