Iraqi police say a bomb explosion in central Baghdad has killed at least 10 people.

The attack Thursday on a market wounded about 20 other people.

The U.S. military also announced that two Marines died due to enemy action in Al Anbar province Thursday.

Meanwhile, thousands of Shi'ite followers of radical cleric Moqtada al-Sadr are converging on Baghdad for a rally Friday to express support for Hezbollah guerrillas fighting Israeli forces in Lebanon.  The U.S. military is tightening security ahead of the rally.

Taro Aso, left, speaks during joint press conference with his Iraqi counterpart Hoshyar Zebari

On the diplomatic front, Japanese Foreign Minister Taro Aso made a brief, previously unannounced visit to Baghdad today.  Aso met with Iraqi Prime Minister Nuri al-Maliki and Foreign Minister Hoshyar Zebari, and announced a $29 million loan to help Iraqi reconstruction.

Japan brought home its 600 troops from Iraq last month, after a two-and-a-half year reconstruction mission.

Meanwhile, news reports say Britain's outgoing ambassador to Baghdad, William Patey, is warning that Iraq is likely to break up along ethnic lines.

The British envoy's comments, in a confidential memo sent to London as he completed his term in Baghdad, were first reported by the BBC.

Some information for this report was provided by AFP, AP and Reuters.