Roadside bombs have killed five US soldiers in a weekend of attacks across Iraq which also claimed the lives of three Iraqi policemen.
US officers say roadside bombs are getting even deadlier
In the deadliest attack, a bomb went off on Friday evening in Tuz, about 180km (110 miles) north of Baghdad, killing three and wounding one.
Iraqi forces report finding a recently dug mass grave during a battle with militants near the capital.
And the US army is investigating a store of chemicals discovered in Mosul.
Few details were released of the latest attacks:
- A bomb attack near the western town of Rutbah on Sunday killed one US soldier and another died in a bomb attack in Baghdad on Saturday
- A US soldier was found dead from a gunshot wound in Baghdad on Friday
- One Iraqi policeman was killed and three wounded by a bomb in Kirkuk and two were found shot dead in Samarra
- A senior official of Iraq's central bank was kidnapped outside his home in Baghdad, police said.
The new US losses bring to more than 1,840 the number of Americans killed in Iraq since the March 2003 invasion.
Several dozen have been killed this month alone.
Bomb attacks on US convoys have doubled in the past year to about 30 a week, according to the Pentagon's top logistics officer in Iraq.
"It's about a 100% increase from last year," Brig Gen Yves Fontaine said on Friday.
A mass grave found near Baghdad at Awereej contains the decomposed bodies of 30 people, including two women, Iraqi security forces said.
The chemicals were found on Tuesday after a tip-off
One report quotes police as saying the grave is about six months old.
Iraqi officials said it had been discovered during an operation against insurgents in which one suspect was killed and 13 others, including an Egyptian and a Sudanese man, were arrested.
Mass graves have been uncovered across Iraq since the invasion but most date back to Saddam Hussein's rule.
A store of chemicals found in the northern city of Mosul may have been earmarked by militants for use in attacks, a Pentagon official said.
Troops raided the store after a tip-off and found about 5,675 litres (1,500 gallons) of various chemicals which are now undergoing tests.
Col Henry Franke, a Multi-National Corps nuclear, biological, and chemical defense officer, said: We are continuing to investigate the production and storage facilities to determine what type and quantities of chemicals were produced at the facility."