Bombings in two crowded Iraqi markets have killed at least eight people and wounded dozens of others.
The attack in Mosul left a deep crater in the tarmac
The first was a car bomb in Mosul in northern Iraq which caused five deaths. It was followed by the second deadly attack in Mahmoudiya in as many days.
Meanwhile, the US military announced that insurgents had killed two of its troops in Iraq in separate incidents.
A soldier was killed when a roadside bomb struck his vehicle and a marine died in combat, statements said.
The wave of sectarian and anti-US violence in Iraq peaked on Saturday when a huge blast killed at least 66 people in a market in a Shia Muslim area of eastern Baghdad.
A website run by a Shia militia said it had detained four people in connection with the attack - two from Diyala Province north of Baghdad, an one Egyptian and a Sudanese.
The Mahdi Army website said the men would be hanged in public if they confessed. This was denied by a spokesman for the Mahdi army leader, radical cleric Moqtada Sadr, who said they would be handed over to the interior ministry.
Officials in Mosul said the car bomb had meant to target a police patrol but most of the casualties - including 28 people wounded - were civilians.
In Mahmoudiya, the same market was the scene of a blast on Sunday night and another about midday on Monday.
Each attack killed at least three people and wounded about 20 others.
The marine was killed in the western Anbar province on Monday, while a roadside bomb hit a US army vehicle, killing one of its occupants, in an area north of Baghdad on Sunday.
The killings of American troops raise the number of US military deaths in Iraq to at least 2,529 since the 2003 US invasion to overthrow Saddam Hussein.
Tens of thousands of Iraqi civilians, security forces and insurgents have been killed in the same period.
In other violence, a Sunni district in northern Baghdad erupted into fierce clashes between government troops and gunmen on Sunday, after rockets landed near the Abu Hanifa mosque, one of the country's most revered Sunni Muslim sites.
The area is reported to be calm a day later, but sectarian tensions remain high across the capital, correspondents say.
Prime Minister Nouri Maliki, a Shia Muslim, has been trying to win backing for a national reconciliation plan designed to dampen sectarian violence.
However, the country's main Sunni political faction has said it will boycott parliament until the release of a female Sunni MP, Tayseer al-Mashhadani, who was kidnapped on Saturday with seven of her bodyguards.
Also on Monday, US forces in Iraq handed over security responsibility in large parts of Diyala province under a gradual plan return control to Iraqi forces.
The US military said its forces would still be available to support Iraqi troops if needed.
The transfer of authority took place at Kirkush military training base, known as Forward Operating Base Caldwell.
The handover came a month after more than 20 people were killed by armed men at makeshift checkpoints in Diyala.
In June, Muthanna province in southern Iraq became the first Iraqi province to be handed back to Iraqi security control.