BAGHDAD - Mortar rounds crashed into the U.S.-controlled Green Zone yesterday - the second such barrage in a 12-hour span - and gunmen ambushed Shiite travelers as part of attacks that killed at least 44 people nationwide.

One of the mortars hit within 100 yards of Prime Minister Nouri al-Maliki's office, an Iraqi official said. The U.S. military reported no casualties in the two attacks, but did say that a soldier died yesterday of non-battle causes. No other details were given.

Although such strikes on the Green Zone have been common, the latest occurred despite the ongoing U.S.-led security crackdown and suggested that extremists have not been daunted by the nearly 11-week operation. The attacks appeared to come from a mostly Shiite district.

In areas outside Baghdad, roads were stalked by suspected Sunni gunmen.

At least 11 Shiites were killed and three wounded after attackers flagged down their bus near Iskandariyah, 30 miles south of Baghdad. About 45 minutes later, gunmen opened fire on civilian cars about six miles to the north near Latifiyah, killing three people and wounding five, police said.

Elsewhere, suspected Sunni militants seized four fuel trucks near Fallujah, 40 miles west of Baghdad, and killed the four drivers, police said.

At least 23 tortured bodies also were found around Iraq - 15 in Baghdad - the apparent victims of so-called sectarian death squads.

Despite the ongoing bloodshed, figures compiled yesterday from Iraqi government reports show that the number of Iraqi civilian deaths fell nearly 20 percent from 1,872 in March to 1,501 in April. The number of wounded also decreased - from 2,702 to 2,334 in the same period.

The death toll for Iraqi soldiers, however, rose sharply to 63, compared with 44 in March. The number of wounded soldiers more than doubled to 108, according to the nationwide figures.

The Iraqi army's toll was still well below the 104 American troops who died last month.

The mounting casualties among American and Iraqi troops comes as they are exposed to more dangers trying to regain control of Baghdad.

An Associated Press tally, however, found that the number of Iraqi civilians killed in April was at least 1,648, or just 3 percent fewer than at least 1,701 killed during March. The AP figures are based on daily police reports and information from Iraqi ministry officials.

Numbers for Iraqi civilians killed since the U.S.-led invasion began in March 2003 vary widely and are believed to be vastly underreported, in part because of political pressure.

The United Nations has provided closely watched figures in the past. But last week it said the Iraqi government had refused to provide it with numbers out of fears they would paint a "grim picture" and undermine security efforts. *