BAGHDAD, Iraq (AP) _ Militants in Iraq kidnapped a Pakistani diplomat on his way to a mosque for prayers, and a previously unknown group claimed responsibility for the abduction, Pakistan's government said Sunday.

Also, Iraqi lawmakers, meeting for the first time since choosing Shiite Arab Ibrahim al-Jaafari as prime minister Thursday, called for the security measures taken during parliamentary sessions to be eased to lessen the inconvenience to Baghdad residents.

Those calls came as a car bomb exploded near a U.S. convoy in Baghdad, injuring four civilians, and Iraq's government said a son of one of Saddam Hussein's half brothers had been arrested.

A day after tens of thousands of supporters of a militant Shiite cleric marked the second anniversary of Baghdad's fall with demands that U.S. soldiers withdraw, Iraqi President Jalal Talabani said he opposed that notion.

``I think we are in great need to have American and other allied forces in Iraq until we will be able to rebuild our military forces, rebuild our security forces,'' Talabani told CNN's ``Late Edition.'' ``And ... until we'll be assured that there will be no danger from terrorism and from foreign intervention in our internal affairs.

Malik Mohammed Javed, a deputy counselor at the Pakistani embassy who has lived in Iraq for six years, went missing in Baghdad on Saturday after leaving his home.

Pakistan's Foreign Ministry said in a statement that the Omar bin Khattab group claimed responsibility for the kidnapping. It added that Javed had contacted the Pakistani Embassy in Baghdad and told officials he had not been harmed.

The kidnappers' demands were not immediately clear.

Javed is the fourth Pakistani to be kidnapped in Iraq.

The first was abducted in June but later released. In July, insurgents kidnapped and beheaded two Pakistanis _ Raja Azad, 49, an engineer, and Sajad Naeem, 29, a driver in Iraq. Both were working for a Kuwaiti company here.

The kidnappers in that case _ calling themselves the Islamic Army in Iraq _ demanded that Pakistan promise not to send troops to Iraq.

Pakistan _ a mainly Muslim nation and a key ally of the United States in the war on terrorism _ has refused to deploy peacekeepers to Iraq and has urged its citizens to avoid coming here.

The government also announced the arrest Sunday of Ibrahim Sabaawi, the son of Saddam's half brother, near Baghdad. The statement said Sabaawi was close to the former regime.

``Until his arrest, he had been supporting terrorists and providing them with finances,'' it said.

It was unclear when or where the arrest took place.

The terrorist group al-Qaida in Iraq, led by Jordanian militant Abu Musab al-Zarqawi, in an Internet statement posted Sunday rejected calls by interim President Jalal Talabani for Iraqi fighters to begin talks with the government. Talabani's call was directed only to the homegrown insurgency and not foreign fighters.

``Oh you agents of the Jews and the Christians, we have nothing for you but the sword,'' said the statement, which could not be independently verified. ``We will not stop fighting.''

In a different statement, the group claimed to have kidnapped and killed Brig. Gen. Bassem Mohammed Kadhim al-Jazaari, a Najaf police official, while he was visiting Baghdad.

``He was been interrogated,'' the statement said. ``After his confessions, God's verdict was carried out against him.''

That statement also could not be verified independently. Interior Ministry official Capt. Ahmed Isma'el said al-Jazaari was kidnapped late Saturday in western Baghdad.

Meanwhile, during Sunday's National Assembly meeting, Iraqi parliament speaker Hajim al-Hassani called for relaxing the security measures for parliament. The measures block nearby Baghdad streets and snarl traffic, leading to complaints from residents.

Some lawmakers said they had been insulted and mistreated by Iraqi police at checkpoints, and one female legislator said her weapon had been confiscated.

``These measures are highly exaggerated and they hinder the work of the employees and the movement of the citizens,'' al-Hassani said. ``We asked the security officials to relax these measures.''

Qassim Dawoud, Iraq's minister of state for national security, said, however, that the measures were necessary as long as the assembly continued to convene at the same location. Officials have proposed moving to a new building being used by the Defense Ministry.

``Terrorism is targeting the National Assembly ... and that's why we have to focus on security,'' Dawoud said.

Underscoring security concerns, a car bomb exploded Sunday near a U.S. convoy in Baghdad, injuring four civilians, Iraqi police Lt. Ali Hussein said.

In Baqouba, 35 miles northeast of Baghdad, a car bomb blew up near a U.S. combat patrol, wounding an American service member, the U.S. military said. Two people were taken into custody.

Lawmaker Jalal Eddin al-Sagheer, a senior cleric and member of the Supreme Council for the Islamic Revolution in Iraq, claimed security forces had been infiltrated by members of the former regime.

``This infiltration threatens everyone,'' he said, calling on the assembly to question the Interior Ministry about the issue.

Sabah Kadhim, the Interior Ministry spokesman, declined to comment on the lawmakers' allegations, saying only: ``We respect the parliament, and we will coordinate with it.''

During Sunday's legislative meeting, Foreign Minister Hoshyar Zebari called on negotiators to expedite the formation of the new government.

``We are under pressure,'' he said. ``We have to write the draft constitution by August and we want to meet the deadlines. We cannot afford to waste more time.''

The lawmakers will meet again Monday.

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Associated Press reporters Sadaqat Jan in Islamabad, Pakistan, and Sameer Yacoub in Baghdad contributed to this report.