U.N. Secretary-General Ban Ki-moon voiced continued concerns about security in Iraq even as he announced plans to open a regional support office in Baghdad, part of the U.N.'s efforts to expand its presence in the war-torn country.

"Security is still a problem," Ban said Saturday, as Iraqi Prime Minister Nouri al-Maliki sat beside him in a joint news conference in which the Iraqi premier stressed that gains realized on the security front. The two were speaking after a meeting that grouped top diplomats representing many of Iraq's neighbors, the United States, donor nations and other groups.

Ban emphasized his hope that "more would be done" on the security front and said the U.N. would build its presence on the ground as the situation improved. The U.N. has maintained a reduced presence in Iraq since after an Aug. 19, 2003, bombing at its Baghdad headquarters that killed 22 people.

But Ban stressed that there was clear agreement in the meeting that the international community cannot turn away from Iraq. "Its stability is our common concern."

He said the new regional office in Baghdad would help foster dialogue between these countries and that its framework and other details would be addressed in Turkey during an October ministerial meeting. Another office is also being considered in the southern city of Basra and the office in Irbil, in the north, could be expanded.

"U.N. experience around the world reveals that such offices facilitates communication and helps to maintain coherent direction," he said, according to a statement of his comments to the diplomats.

"This is a plan. We will have to closely monitor the security situations there, including in Basra. We will closely monitor and coordinate with the Iraqi and other (multinational) forces before we take necessary decisions," Ban said.

Ban's comments about security, coming in the same breath as talk of expanding the U.N.'s presence, reflect the challenges confronting al-Maliki's government. It is struggling to stabilize the country while dealing with pressure from Democrats in the U.S. Congress who are calling for the quick withdrawal of American forces.

Al-Maliki, who is in New York for the U.N. General Assembly and is scheduled to meet with U.S. President George W. Bush on the sidelines, acknowledged that the country continued to face challenges, but said that "those following the situation in Iraq have spoken of a marked improvement (in security)."

"National reconciliation does not come about by force," al-Maliki said, referring to the effort to bring together the country's rival ethnic and religious factions. Fighting between Shiite and Sunni Muslims, compounded by attacks from terror groups, has largely undermined Iraq's reconstruction effort.

"The security situation has improved, and the economic situation has also improved and, as a result, thousands of families who left their homes have decided to return to the country," al-Maliki said, refering to some of the hundreds of thousands who have fled the country in the face of daily attacks and other violence.

Earlier Saturday, al-Maliki, in pledging that Iraqi forces would take responsibility for the security of an expanded U.N. mission, had said that the "Baghdad of today is different from the Baghdad of yesterday."

The meeting between al-Maliki, U.S. Secretary of State Condoleezza Rice, Ban and other diplomats sought to build upon a Security Council resolution passed last month which authorized the expansion of the U.N.'s presence in Iraq.

Bringing together neighbors such as Iran and Syria also underscored the importance of a collaborative approach to stabilizing the country, particularly as Damascus and Tehran, respectively, have been repeatedly accused by the U.S. of failing to secure their borders and arming Iraqi militias.

The meeting was also aimed at discussing ways to help Iraq realize economic and political goals laid out in the International Compact with Iraq, a sweeping five-year economic and political reform package Ban helped broker in May in Egypt.

But the tensions between the U.S. and Iran, which the Bush administration has accused of arming Iraqi militias, surfaced during the gathering.

Rice told reporters after the meeting she had been pleased that participants offered their "full commitment" to Iraq, especially through an expanded U.N. mission. Another top State Department official expressed displeasure with Iran's "very long" presentation, saying it was more a rambling complaint about the U.S. than about Iraq issues.

David Satterfield, the department's Iraq coordinator, said it was difficult for the U.S. to take Iran's pledge to work in support of reconciling Iraq's various factions while it continued to arm and train insurgents. Iran denies those charges.

"What they are doing on the ground is that they are continuing to supply arms and training on arms to the most violent, most lethal, most radical elements in Iraq," Satterfield told reporters. "We don't believe this is consistent with a pledge to support reconciliation."

The American concerns were also voiced by the Iraqis, even as al-Maliki described the dialogue as "positive."

George Barqos, an adviser to the Iraqi premier, said Iran's presentation was "not up to standard," pointing out that both Iranian Foreign Minister Manouchehr Mottaki and Syria's representative at the talks indicated that Iraq's security woes stem from the presence of foreign forces.

"We reject interference from neighboring countries with regard to the foreign forces because they are there at the request of the Iraqi government," said Barqos. "We will not allow interference in our affairs just as we will not interfere in the affairs of others."