Three years after a massive earthquake ravaged Haiti, President Michel Martelly said Saturday his country was slowly rebuilding, despite the ongoing day-to-day misery of many survivors.

An estimated 250,000 people were killed in the January 12, 2010 disaster. Hundreds of thousands are still living rough in squalid makeshift camps, and they now face rampant crime, a cholera outbreak and the occasional hurricane.

"I bow in memory of the victims. I can still hear the cries of pain from families who lost loved ones, but dry your tears," a visibly moved Martelly said on the grounds of the presidential palace, which collapsed in the quake.

"Despite all the suffering, Haiti is recovering."

Former US president Bill Clinton was among officials and diplomats attending the somber memorial ceremony in the capital Port-au-Prince, at which a police siren rang out in honor of the dead.

While the presidential palace has been reduced to a heap of stone and metal, "the flag remains aloft and proud," Martelly said, vowing to rebuild his impoverished Caribbean country from the ground up.

The president later laid a wreath at a mass grave north of Port-au-Prince where the remains of tens of thousands of people are buried.

Residents of the capital flocked to the city's churches, singing mournful hymns in memory of lost loved ones.

The rebuilding process has been slow in Haiti, already one of the world's poorest countries when disaster struck three years ago.

Beyond the presidential palace, several other ministries remain in ruins and unusable. The parliament has been razed and Port-au-Prince's cathedral reduced to rubble. Other churches and schools were destroyed.

In tough comments to journalists on the eve of the anniversary, Martelly said he was "not satisfied" with progress, and urged foreign donors to have more faith in his administration to lead reconstruction efforts.

"Where has the money given to Haiti after the earthquake gone?" he asked, charging that only a third of the international aid recorded so far was actually handed over to the Haitian government, and urging an overhaul.

"Most of the aid was used by non-governmental organizations for emergency operations, not for the reconstruction of Haiti.

"Let's look this square in the eye so we can implement a better system that yields results."

The European Union pledged another $40.7 million in help, with aid commissioner Kristalina Georgieva saying the bloc is "committed to helping Haitians in need and the country with its reconstruction."

In the past two years, hundreds of housing units have been built, and the government has set up shop in prefabricated buildings, the best option until ministries can be rebuilt. But the reconstruction process has been slow.

"We have recorded damages of nearly $13 billion," said Martelly, who came to power in the nation of 9.8 million people a little over a year after the quake.

"My dream is to see the country turn into a sprawling construction site."

In the streets of Port-au-Prince, however, Haitians say they have waited long enough.

"If our leaders don't do something to get us out of these tents, we will take to the streets one day," said Jacky, an unemployed father of three.

Ary Adam, who is in charge of the office tasked with the reconstruction of public buildings and housing, said Haiti needs 400,000 homes to house the 1.5 million people left homeless by the quake.

But the money is not there. Adam says private investment may be a solution, but not in the short term.