The United Nations Secretary General Kofi Annan has announced he will visit Lebanon to commence an extensive regional tour to firmly establish the UN-brokered truce.
The announcement follows the pledge by EU nations last week to support a peacekeeping team by providing thousands of troops for an expanded UN force in south Lebanon.
The UN chief's talks will focus on the deployment and position of the 15,000-strong force, which will be sent to help stabilise the ceasefire between Israel and Hezbollah.
It is also thought that Annan will be asked to help bring about a prisoner exchange with Israel as demanded by Hezbollah.
Annan will arrive in Beirut on Monday morning for talks with Prime Minister Fuad Siniora, Mr Berri and other politicians. It is not known whether he will meet Sheikh Nasrallah, who said he would welcome talks.
The UN is hoping to have some of the troops on the ground within a week, although the EU says it will be two to three months before the whole force is deployed.
Annan has made clear that UN troops will not be asked to disarm Hezbollah by force.
After his visit to Lebanon, Annan will travel to Israel, the Palestinian territories, Syria and Iran. Annan has not visited Iran since the election of Mahmoud Ahmadinejad as president in 2005.
A previous trip was cancelled after the Iranian leader called for Israel to be "wiped off the map". But officials at the UN in New York insist that the Iranians need to be "part of the current dialogue" on the Middle East, a BBC correspondent has reported.