BAGHDAD, Iraq (CNN) -- At least two Iraqi police officers were killed and 13 others wounded Tuesday when a suicide car bomb exploded outside the home and office of a former Iraqi prime minister, an Interior Ministry official said.
Former Prime Minister Ayad Allawi's party released a statement after the blast saying officials warned the U.N., U.S. forces and the Iraqi government that insurgents were planning attacks against Allawi and his Iraqi National Accord bloc.
"Unfortunately no action was taken," according to the statement, which warned that future attacks are anticipated.
"We expect these terrorist attempts to continue, and these enemy forces will not stop until they are successful in their attempts against Dr. Allawi and the INA to try to extinguish the voice of national unity," the statement said.
The blast erupted about 8:20 a.m. on the edge of Baghdad's heavily fortified International Zone, outside a police checkpoint near the homes and offices of Allawi and Saleh Mutlaq, a prominent Sunni politician, the official said.
The International Zone, also known as the Green Zone, is the seat of U.S. military and diplomatic agencies, as well as the Iraqi government and parliament.
The offices were part of the Iraqi National Accord headquarters. The political party is secular.
Speaking from Jordan, Al-Mutlaq said he was not at home during the attack because he had received information that terrorists had recently infiltrated the area. The politician's home doubles as an office for his Iraqi National Dialogue party.
The bomber saluted the guards posted outside the homes, but failed to stop at a checkpoint, al-Mutlaq said, recounting what he was told about the incident. When the guards opened fire, the driver swerved off the main road and the car exploded near a checkpoint between the homes, al-Mutlaq said.
The statement from the National Accord office suggested the Iraqi government was to blame for failing to provide protection. The statement also called for outside intervention to stem the violence plaguing Iraq.
"We hold the Iraqi government responsible for protecting political figures and political parties, and again we request they provide means so that they can protect themselves, their offices and their residences," the statement said.
It continued: "We request from the United Nations, the Arab League and the Organization of the Islamic Conference to intervene to stop the flow of Iraqi blood and to help put an end to these criminal acts that have claimed the lives of thousands of Iraqi civilians."
Al-Mutlaq and Allawi both have been critical of the present Iraqi government.
Allawi, who served as the war-ravaged nation's first post-invasion prime minister, has said Prime Minister Nuri al-Maliki should resign because his government is loyal to Iranian and Shiite militias.
Al-Mutlaq says the Iraqi government is unable to establish security because of widespread corruption and because the Interior Ministry security forces have been infiltrated by militias.
In other developments:
• Iranian President Mahmoud Ahmadinejad said he is planning to visit Iraq, though he did not reveal a timetable. In a Tuesday news conference in Tehran, Ahmadinejad spoke optimistically about Iranian relations with the U.S. after an intelligence finding that his country suspended its nuclear weapons program in 2003. He stopped short of saying he would enter into direct talks without preconditions.
• Gunmen fatally wounded a prominent Iraqi doctor Monday night in eastern Baghdad's Baladiyat neighborhood. Dr. Ibrahim Mohammed Ajil was driving home from his job as the head of al-Rashad Psychiatric Hospital, an Interior Ministry official said. The doctor died Tuesday morning.
• A U.S. soldier was killed and two others were wounded Monday by a suicide car bomb in Salaheddin province, north of Baghdad, a U.S. military statement released Tuesday said. All were members of the U.S. Army's Task Force Iron. Since the start of the war, 3,888 U.S. troops have died in Iraq, including seven in December. E-mail to a friend
CNN's Jomana Karadsheh contributed to this story.