Jean-Max Bellerive told an emergency meeting of ministers in Montreal, including US Secretary of State Hillary Clinton, that the "colossal" effort would take "at least five to 10 years".
He said: "The people of Haiti will need more and more and more in order to complete the reconstruction. What we're looking for is a long-term commitment. Haiti needs the massive support of its partners in the international community in the medium and long term."
Responding to criticism that the Haitian government had been almost invisible during relief efforts he said it was working in "precarious conditions".
"We are fully conscious that the prime responsibility for our future lies in the hands of the Haitian government and the Haitian people."
Canadian Prime Minister Stephen Harper said: "It was not an exaggeration to say that at least 10 years of hard work awaits the world in Haiti."
Officials from a dozen countries, the United Nations, the European Union and the International Monetary Fund attended the talks to discuss the aid effort and make initial rebuilding plans.
They looked at whether to relocate the capital Port-au-Prince away from its present site. Around 235,000 survivors have already fled the blighted city.
The Montreal talks were expected to lay the groundwork for a full-fledged donors conference in the coming weeks at which pledges of money for reconstruction will be made.
Diplomats raised the possibility of a rebuilding project similar to the Marshall Plan, the US-led postwar reconstruction of Europe, which would take many years.
Nearly two weeks after the worst recorded disaster in the Americas there was still confusion over the death toll. One Haitian minister said 90,000 bodies had been collected, another said 150,000. One third of the buildings in Port-au-Prince are destroyed and at least one million people are homeless.
Haiti was already the poorest country in the Western hemisphere and groups including Oxfam and The World Council of Churches called on ministers to immediately cancel its full $890 million (£550 million) international debt.
They also asked for delivery on the IMF's previous pledge to turn a $100 million (£62 million) interest-free loan to into a grant.
Oxfam International executive director Jeremy Hobbs said: "Expecting Haiti to repay billions of dollars as the country struggles to overcome one of the worst natural disasters in recent memory would be both cruel and unnecessary." Britain has already cancelled all debts owed to it by Haiti and called on all remaining creditors to do the same.
With the planting season just two weeks away Oxfam also called for support for Haiti's farmers to prevent a man-made food crisis. There were also calls for cash grants which would be used to pay earthquake survivors to clear up the rubble.
There has already been widespread criticism of the relief effort in Haitiwhich came under further attack from Italy's civil protection chief, Guido Bertolaso. Mr Bertolaso was acclaimed for his handling of the aftermath of last April's earthquake in L'Aquila, Italy.
In an extraordinary outburst in Port-au-Prince he called the US-led effort in Haiti a "pathetic" failure, saying it was too reliant on military personnel. The US has sent 20,000 troops and anchored a hospital ship offshore.
He said: "I think it has truly been a pathetic situation. It could have been run a lot better, "The Americans are extraordinary but when you are facing a situation in chaos they tend to confuse military intervention with emergency aid, which cannot be entrusted to the armed forces.
"It's a truly powerful show of force but it's completely out of touch with reality." Mr Bertolaso, who holds the rank of a government minister, also accused individual countries and aid agencies of conducting a "vanity show".
He said: "Unfortunately there's this need to make a 'bella figura' before the TV cameras rather than focus on what's under the debris." The Italian Government immediately distanced itself with a clearly embarrassed Franco Frattini, the foreign minister, saying: "The Italian government does not share these statements." Meanwhile, the UN and children's charities criticised plans by the US, Belgium, France, Germany, the Netherlands and Spain, to fast-track adoptionprocedures for taking orphans out of Haiti.
"We are very concerned that there are increasing reports that children are being picked up and trafficked out of the country," said UNICEF spokesman Kent Page, although he had no details of specific cases.
There was also disagreement over a plan by European countries to send 350 police officers to help with aid distribution as looting continued in Port-au-Prince.
Six countries - France, Italy, Spain, the Netherlands, Portugal and Romania - agreed to send officers but Britain opposed the idea, saying the US had enough troops there already.