The mutilated bodies of 10 Iraqi Shia Muslim pilgrims have been found in the desert near the town of Qaim, close to the Syrian border, Iraqi police say.
They are thought to have been killed as they travelled back from Syria.
The murdered pilgrims had apparently been blindfolded, tied up and shot in the head, police said. The corpses bore marks of torture.
In other violence, seven people died in two suicide bombings in the northern town of Sinjar, officials said.
The dead Shia pilgrims are thought to be from southern Iraq.
Iraqi officials said they believed the Shias were stopped as they were on their way back from visiting a religious shrine in Syria several days ago.
They were attacked in the area where the US military carried out a major operation against insurgents earlier this month.
The new Shia-dominated government unveiled a month ago is facing a determined campaign of violence with attempts to fuel sectarian tensions, says the BBC's Caroline Hawley in Baghdad.
Almost 700 Iraqis have been killed since the government took office.
Earlier on Saturday, two bombs exploded in quick succession near a military base in Sinjar, about 120km (75 miles) north-west of Mosul, Iraqi officials said.
Seven people were killed and more than 50 wounded, many of them civilians working at the Iraqi base and also two small children, doctors said.
"The first car exploded at 0820 (0420 GMT) at the entrance to the base used by Iraqi soldiers and border guards," said police officer Qassem Jaber.
"A few minutes later, the second bomb exploded in the same place."
The Iraqi army is frequently targeted by insurgents, who regard its soldiers as collaborators with the US military.