A bomb strapped to a motorcycle exploded in the center of the capital Thursday, killing at least 12 people and injuring 29, police said. At least 13 other people were killed or found dead in various parts of the country.

The attack near Rusafi Square in the shopping area of Rashid Street apparently targeted vendors and commercial stalls, said police Lt. Ahmed Mohammed Ali. He said the bomb was hidden in a parked motorcycle.

Several shops caught fire and many of the victims were seen being driven in private cars to hospitals as ambulances were obstructed by concrete road blocks and razor wires.

The attack occurred as Japanese Foreign Minister Taro Aso was visiting Baghdad on a surprise trip. At a news conference, he announced a $29 million loan for the reconstruction of Iraq.

CountryWatch: Iraq

The road to recover for Iraq's economy has been a slow one because of the continuing violence, blamed on sectarian divisions between Iraq's Shiites and Sunnis. It has taken the shape of almost daily bombings, shootings, abductions and assassinations.

On Thursday, gunmen shot to death four people in separate incidents in Baghdad, Amarrah, Mosul and Basra, police said. Also Thursday, the bodies of nine men were found floating in separate places in the Tigris River, police and morgue officials said. At least two of the bodies were blindfolded, bound and shot.

According to figures compiled from Iraqi security and health department figures, more than 1,000 civilians, 135 members of security forces and 143 insurgents were killed nationwide in July. In addition, 1,800 civilians were injured.