Clad in white, hundreds of thousands of Haitians congregated throughout Port-au-Prince yesterday for tearful ceremonies to mark one month since a cataclysmic earthquake shattered their country.

In the central Champ de Mars square, where the impact of the 7.0 magnitude temblor is still seen in the sprawling tented camps that now dominate the plaza, people began to gather from before dawn.

Part memorial service, part rally, mourners gave resilient cries of "hallelujah" as others wept for loved ones lost in an event many simply call "the catastrophe."

Some 217,000 people are reported to have died as a result of the January 12 quake and an estimated 1.2 million people remain homeless, including 650,000 children.

The government declared yesterday a day of mourning as many businesses shuttered and most of Port-au-Prince's normally bustling streets were eerily quiet.

But streets leading to the Champ de Mars and other gatherings filled with throngs of people - dressed in traditional funeral colours, black and white - travelling by foot, taxi and motorbike to take part in a spectacular outpouring of emotion.

"Today there are many children who have lost their parents" a preacher in the Champ de Mars said. Looking back at him the crowd carried expressions of intense suffering.

"All the religions of Haiti - Voodoo, Catholics, Baptists, Protestants, we are all gathered here to pray" he said into a microphone "the Haitian people may be poor but they are richest in the world in grace and spirit." At Notre Dame university, President Rene Preval sat sorrowfully in a white shirt and black arm band, joined by his wife and top government officials as a brass-rich orchestra played a sombre rendition of 'Amazing Grace'.

"Today, allow me to address you as Rene Preval the citizen, the man and the father of a family, to tell you there are no words to describe this immense pain."

Mr Preval's government, itself decimated by the powerful quake, has for a month struggled in make-shift offices to help the already impoverished country rise to its knees.

"Haiti will not die, Haiti must not die," he said at the ceremony, which was broadcast nationally.

Not far from the capital, at Titanyen, where thousands of quake victims were buried in mass graves, there was silence, but for a few mourners.

Three local men pulled up in a white truck, one carrying a small Haitian flag, to pay their respects.

"We came here to do something for the memory of the dead," said Joseph Gesner Saint Louis, 35, adding proudly "we are Haitians."

In Petionville, a once a well-to-do suburb of the capital, another group gathered at the centre of a crowded camp to hear a Protestant preacher lead prayers.

While hundreds of people dressed in white pressed toward the band that led them in prayer, others simply arose in the web of tarpaulin and sheets where they slept.

But amid the mourning, some activities continued.

Near the other side of the camp, men waited in their Sunday best as their wives collected rice at one of the distribution points that help keep the destitute alive. The recovery effort has seen a massive outpouring of support from the international community, as individuals around the globe also dug deep into their pockets to help a country and people most have never seen.

But even a month after the quake the need for basic items was acute.

"We haven't even gotten water," said 27-year-old mother of two Carline Nazaire.

The UN's humanitarian chief, John Holmes, was due to arrive in Haiti yesterday as part of a three-day visit to see the massive aid effort.

The urgency of his mission was underlined Thursday by an early morning downpour, and heavy rain clouds that clung ominously to the mountains over Port-au-Prince for much of the day.

Aid agencies fear the rainy season could bring more cases of diarrhea and other water-borne diseases in the crowded camps, which have few latrines and are often flooded with refuse and human waste.

An estimated 50,000 families, or about 272,000 people, have received emergency materials to build their own shelters, according to the UN office that coordinates humanitarian affairs.

Haitian authorities have warned the rainy season, which starts in March, is now the greatest threat the impoverished Caribbean country faces.