The family member also said that one of the abductees had been shot as he tried to resist. It was unclear what his condition was, agency reports said.
"Iraq is still under foreign occupation and Iraqis continue to die in great numbers"
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Interior ministry and police sources had no immediate information.
The group had met on Saturday with the tribal adviser for Nuri al-Maliki, Iraq's prime minister, inside Baghdad's heavily fortified Green Zone.
Tribal leaders and some armed groups in Diyala have joined the US and Iraqi security forces in trying to eradicate al-Qaeda from Diyala - a religiously diverse province that has witnessed sectarian violence in the past few years.
Meanwhile, a car bomber killed at least six people in an explosion that ripped through shops and set cars ablaze in the north of Iraq on Sunday, police said.
Major-General Torhan Abdul-Rahman, the deputy police chief of Kirkuk, said that nearly 30 people were also wounded in the blast.
| Police said 25 shops and 10 cars near a bus terminal were destroyed [Reuters]|
Kirkuk, known as the oil centre of the north, is claimed by both Kurds and Arabs.
The regional centre has had a series of bomb attacks and shootings recently
Clouds of dense, black smoke rose into the sky as firefighters, helped by residents, tried to put out the flames.
The explosion left twisted wrecks of cars scattered in the street, amid the blackened ruins of the shops.
A police official said 25 shops and 10 cars near a bus terminal in the Kurdish area of al-Haseer were destroyed.
A motorist who preferred anonymity said the blast shattered the windows of his car and he was wounded by flying glass.
"Kirkuk is not a place to live any more. Wherever you go there are roadside bombs and car bombs. The security forces cannot find a solution for the terrorism," he said.
Kirkuk, which sits on Iraq's northern oilfields, is shared by Kurds, Turkmen, Shia and Sunni Muslims.
Kurds want it to be incorporated into their largely autonomous Kurdistan region, but Arab residents oppose this.
A referendum on the issue, due by the end of the year, is expected to be delayed until 2008.
Kirkuk's police chief escaped a car bomb attack on his motorcade earlier this month in which seven people were killed and 50 wounded.