A suicide bomber on a motorcycle struck a checkpoint in Baghdad manned by United States-backed neighbourhood guards on Sunday, killing 15 people and wounding 29, police said.
Among those killed in the attack in the mainly Sunni Arab Adhamiya district of northern Baghdad was a leader of the neighbourhood guards in the area, Faruq Abu Omar.
The bomber rode up to the checkpoint on a motorcycle and detonated a vest packed with explosives, police said.
The guards, known as "Sons of Iraq", are paid by United States forces to protect neighbourhoods in areas where local tribes have turned against al Qaeda Sunni Arab militants. The militants frequently strike their checkpoints.
Iraq has become far less violent over the past year, but US and Iraqi forces say al Qaeda is still able to carry out car bomb and suicide attacks.
Meanwhile, a Taleban suicide bomber has rammed an explosives-packed car into the gate of the main United States military base in southeastern Afghanistan, killing nine civilians and wounding 13.
The bombing comes at a time of heightened security as military and diplomatic officials issued warnings that intelligence reports indicate the al Qaeda-backed Taleban is planning a big attack to coincide with Independence Day celebrations on Monday.
Officials said two more suicide bombers in another car approached the base near the southeastern town of Khost as security forces dealt with the aftermath of the first attack, but were shot dead by police before they were able to detonate their explosive.
The Taleban claimed responsibility for the blast.