At least four people have been killed in a number of bombings in Iraq.
Friday's bombs were the latest in a new wave of Baghdad attacks
The worst attack was in Samarra, where a roadside bomb killed Iraqi soldiers, the Iraqi army said.
A suicide bomber killed himself and injured five in Baghdad's Mansour suburb, while a roadside bomb in the east killed one and injured three.
The attacks came a day after a double suicide car bombing in heavy traffic in central Baghdad killed at least 15 people and wounded more than 30.
Statements on Islamist websites said that al-Qaeda in Iraq, headed by Jordanian militant Abu Musab al-Zarqawi, carried out both Thursday's and Friday's Baghdad attacks.
American and Iraqi officials had reported something of a downturn in insurgent attacks over the past couple of months.
But the BBC correspondent in Baghdad, Jim Muir, says the impression in recent days is that the tempo may be starting to pick up once again.
On Thursday evening, at least 12 people at Camp Bucca - Iraq's largest US-run jail - were hurt after the murder of a prisoner sparked a mass brawl.
The fighting at Camp Bucca, near the south-eastern Iraqi port of Umm Qasr, was not directed at US guards or prison staff, the US military said in a statement.
According to the statement, a fight broke out between inmates after the murder of a man inside the compound.
It follows a big riot at the camp two weeks ago. Stones were thrown and tents were burned after word spread that a supporter of radical Shia cleric Moqtada Sadr had been denied medical treatment.
The US holds 6,000 mainly Iraqi detainees at Camp Bucca.