UN vows to broaden role on Iraq
eed better security.
The UN withdrew most of its staff in 2003 after a bomb killed its top envoy and 21 others but Iraqi PM Nouri Maliki says he can now guarantee UN security.
Iraq, its neighbours and major donor nations are attending the meeting.
Mr Ban described the talks, which he co-chaired with Mr Maliki, as "positive and supportive".
Mr Ban said: "There was a clear agreement that the international community cannot turn away from, or ignore Iraq. Its stability is our common concern."
UN AUGUST RESOLUTION
Authorises UN envoy to help Iraqi government in political, economic, electoral, constitutional, refugee and human-rights issues
Promotes talks among ethnic and religious groups
Promotes talks between Iraq and neighbours on border security, energy and refugees under UN auspices
Raises UN staff in Iraq to 95
BBC diplomatic correspondent Jonathan Marcus says Mr Ban's tone was emphatic - the time for collective action had come.
The secretary general said there would be a new "regional support office" in Baghdad to foster dialogue between involved countries and an office in the southern city of Basra was also being considered.
But our correspondent says it is clear that security will be the principle factor governing the scale and pace of any expanded UN role.
The bombing of the UN's Baghdad headquarters in 2003, with the loss of envoy Sergio Vieira de Mello and 21 others, has meant there is now only a small presence in the country.
After a meeting with Mr Ban, Mr Maliki said the security situation had "improved a lot in Baghdad".
"We are going to be able to provide security to the UN in a way that will allow it to perform its role in an effective manner," he said.
A greater UN role was called for in a Security Council resolution in August.
Mr Ban said peace could not come through military action alone
Mr Ban also said peace in Iraq could not be attained through military means alone and that regional cooperation was vital.
The talks have also been focusing on improving the economy, development and security of Iraq, and on stabilising the political situation and ending sectarian strife.
How to deal with the humanitarian crisis is another key issue.
There are more than two million Iraqi refugees who have fled the country, as well as two million who are displaced within Iraq.
Key economic powers like Germany and Japan; regional players like Saudi Arabia and Iran; and representatives from international economic organisations like the International Monetary Fund and the World Bank have all been at the meeting at UN headquarters.
US Secretary of State Condoleezza Rice is also attending.
Our correspondent, Jonathan Marcus, says the August UN resolution underscored the shifting approach of the US administration to Iraq.
He says the US is desperate to reduce its military entanglement in Iraq, believing that regional countries have a role to play in reducing violence there.