Lawmakers allied to Prime Minister Nouri al-Maliki said Tuesday that negotiations over a U.S.-Iraqi security pact and the future status of American troops in Iraq were stumbling, with "almost all points under dispute."

Dawa party lawmaker Haidar al-Abadi told reporters in Baghdad's U.S.-guarded Green Zone that "almost all American suggestions were countered by different Iraqi ones."

"The negotiations are at a standstill, and the Iraqi side is studying its options," al-Abadi said, reading a statement from his party.

The agreement, which both sides hope to finalize this summer, would outline the long-term security relationship between Iraq and the United States and provide a legal basis for American troops to stay in Iraq after their U.N. mandate expires at the end of the year.

U.S. Embassy spokeswoman Mirembe Nantongo described talks over the pact as "active" and said Tuesday that "texts are very much in flux."

"One thing I can affirm is that a fundamental principle underlying these negotiations is our recognition of and respect for the fact of Iraqi sovereignty," Nantongo said in response to an e-mailed request for comment. "There is no question of the U.S. forcing anything."

The U.S. State Department's top Iraq adviser, David Satterfield, met Tuesday with Iraqi Foreign Minister Hoshyar Zebari, whose office issued a statement afterward saying the two "discussed efforts to ensure Iraq's rights and its full sovereignty."

Both sides also pledged to try to finish the agreement on time, it said.

But al-Abadi, a Shiite legislator close to the prime minister, said talks have hit major stumbling blocks over the future status of U.S. military bases and American use of airspace over Iraq.

"The Americans have some demands that the Iraqi government regards as infringing on its sovereignty," al-Abadi said. "This is the main dispute, and if the dispute is not settled, I frankly tell you there will not be an agreement."

Al-Abadi said Iraq insists that Washington pay fees for each of its military bases in Iraq, as well as promise not to hold the bases permanently or even long-term.

Iraqi government spokesman Ali al-Dabbagh also issued a statement Tuesday saying al-Maliki's Cabinet discussed the proposed security agreement and "affirmed not to accept any article that undermines the national sovereignty."

Also Tuesday, the U.S. military said it killed four militants in Baghdad and captured two Al Qaeda in Iraq bombing suspects and a Shiite militia leader in separate raids north and south of the capital.

U.S. soldiers fatally shot the four men after coming under machine-gun fire before dawn Monday in an eastern Shiite district of Baghdad, the military said. They also seized 18 AK-47 semiautomatic weapons and several rounds of ammunition, it said.

One of the Al Qaeda suspects, arrested Tuesday along with four aides, is believed to oversee security for Al Qaeda's Iraq branch in Mosul — one of the terror network's last urban strongholds where U.S. and Iraqi forces have waged fierce battles against militants in recent months.

The man is also suspected of masterminding bombings targeting Iraqi police in the area, according to a U.S. military statement.

The other Al Qaeda in Iraq suspect was captured Tuesday along with an assistant in Tikrit, a Sunni Muslim city north of the capital. He allegedly facilitated suicide bombings and "foreign terrorist movement" for Al Qaeda, the statement said.

The military said it also captured a suspected Shiite militia leader Tuesday south of Baghdad.

The U.S. refers to such fighters as members of Iranian-backed "special groups" who are defying a cease-fire order by anti-American cleric Muqtada al-Sadr. Many of them are believed to have fled recent fighting in Baghdad's Shiite militia stronghold of Sadr City.

The man and five associates surrendered without incident at his home in Kut, southeast of the Iraqi capital, a separate U.S. military statement said. He is accused of involvement in the murder of Iraqis and American soldiers, it said.

Witnesses in Mosul, meanwhile, said Kurdish troops reinforced positions Tuesday at Iraqi government buildings in the northern al-Arabi district, deploying fighters to rooftops despite an order from al-Maliki to vacate the area.

"We've seen an intensified presence of peshmerga (Kurdish militia), and their numbers have increased along with armored vehicles," one resident said on condition of anonymity out of fear of reprisals. He added that government troops had also increased their patrols.

The recent fighting in Mosul has been mainly to quash Al Qaeda in Iraq militants, but the city also suffers from tension between Kurdish and Sunni Arab factions.

The discord stems largely from lopsided political representation in local government, which is dominated by Kurdish parties and their allies even though Arabs hold a slight majority in Mosul's province, Ninevah. Sunni Arabs boycotted the last provincial elections in 2005.

On Tuesday, Mosul's deputy governor, a Kurd, denied any standoff the government forces.

"We are national political parties participating in the government and not fighting its forces," said deputy governor Khisro Koran. "We support the government and its security measures so that we are not excluded."