The government also wants financial aid to help cover the costs of the July-August war between Hezbollah and Israel.
Ban Ki-moon, the UN secretary-general, who will take part in the Paris conference, called Lebanon "one of the most important, serious areas to which the international community needs to pay attention and cooperate".
He told a news conference on Wednesday after talks with EU leaders in Brussels that the international community needed to help the government "restore political and social and economic stability".
The EU executive said it would pledge nearly 400 million euros ($520 million) more in grants and loans to bring to 500 million euros ($650 million) the total it had provided to Lebanon since last summer.
The additional funds will be for the period until 2010 and will cover not only immediate post-war reconstruction, but also assistance for a longer-term recovery through support for political and economic reforms.
Fuad Siniora, the Lebanese prime minister, left for Paris on Wednesday and met Jacques Chirac, the French president.
A spokesman for the French presidency said following the meeting that Chirac had pledged to loan 500 million euros ($650 million) to Lebanon.
"France will bring Lebanon its support in the form of a 500 million euro loan, extended on highly preferential terms," said the spokesman.