BAGHDAD - A bomb exploded Monday at a wholesale produce market in southern Baghdad, killing four people and wounding 14, Iraqi police officials said.

The blast was the latest in sporadic but often high-profile attacks that result in large casualty tolls that continue to plague the country, despite a sharp overall drop in violence in Iraq in May.

At least 165 Iraqis were killed in May in war-related violence, including 31 Iraqi security forces and 134 civilians, according to a tally by Iraq's government. That compared to at least 355 reported killed by the ministries in April, the deadliest month in Iraq this year.

Monday's blast occurred shortly before 8 a.m. at the Rasheed market in Baghdad's southern Dora neighbourhood -- the same market that was the scene of a car bombing last month that killed 15 people and wounded nearly 50.

Sectarian tensions remain high in Dora, a mostly Sunni district with some Shiite enclaves. Its wholesale market has been a repeated target of insurgents over the years, partly because of its popularity.

An Iraq police official said the bomb was planted near the front gate of the market, and exploded as trucks carrying fruits and vegetables were waiting to enter with their goods. The official spoke on condition of anonymity because he was not authorized to release the information to the media.

Fruits and vegetables were scattered amid burning vehicles near the gate.

Falah Amer al-Jubouri, the owner of a shop inside the market, said he was bargaining with wholesale sellers about prices when the blast went off.

"I heard a big explosion, followed by a ball of fire and smoke billowing up," he said. "Everyone rushed outside to see burning cars with dead and wounded people trapped inside them."

Al-Jubouri said people at the market rushed to put out the fires and help the wounded before Iraqi firefighters and ambulances arrived.

Witnesses also said there were no Iraqi or U.S. forces present at the time of the explosion.

In last month's attack, the car bomb went off also near the entrance of the market. A second car bomb was found later in the area and defused.

Also Monday, a suicide car bomb exploded at a police checkpoint in Jalula, 125 kilometres northeast of Baghdad, killing a 7-year-old child and wounding eight other people, an Iraqi police official said.

The official said the bomber appeared to be trying to target a nearby police station but detonated the car when he was confronted at the checkpoint by police, who opened fire at him, said the official. The official spoke on condition of anonymity for the same reason as his colleague in the Dora blast.

The casualty tally by Iraq's government was taken from numbers provided by the departments of interior, defense and health. Officials at the three ministries provided the tally on condition of anonymity because they also were not authorized to release the information.

The security personnel include Iraqi military, police and police recruits, and bodyguards. Insurgent deaths are not included.

Last month, the ministries reported at least 355 killed in April, including 65 security forces and 290 civilians.

Twenty-four American troops were killed in Iraq in May, making it the deadliest months since last September when 25 were killed.

At least 4,306 members of the U.S. military have died in Iraq since the war began in March 2003, according to an Associated Press count.