LEOGANE, Haiti (AP) — Former US President Jimmy Carter yesterday urged donors to honour the billion-dollar pledges they made to help Haiti rebuild after its devastating 2010 earthquake.

Carter's call for greater humanitarian aid to Haiti came on the first day of a weeklong effort to build 100 homes with about 600 volunteers from Habitat for Humanity.

It was the second time in the past year that Carter, 88, and his wife Rosalynn have come to help house people displaced at the epicentre of the disaster.

"We've seen numerous governments in Haiti; they have a very difficult time," Carter told reporters, noting this was his 11th trip to Haiti. "I think we should give the government of Haiti some breathing room and give them all the support we can, even if there's some waste of money."

Donor nations and institutions promised US$4.46 billion to help Haiti after the quake. But only a little more than half of that money has been released, according to the UN Office of the Special Envoy for Haiti.

The reasons for the delays vary, ranging from economic problems back home to a wait-and-see approach until the Haiti's government gets settled. President Michel Martelly took office in May 2011 but much of his first year was spent without a Cabinet because of political paralysis and infighting.

Carter and the former first lady joined in the construction of the 100 houses on about 14 acres, hammering away and measuring facades. The Carters and fellow volunteers also built 100 homes during a visit a year ago. The effort will result in about 250 homes in total for what organisers say will be a new community, complete with agriculture production.

Still vast numbers of Haitians remain without permanent housing. About 369,000 people live in the tent and tarp settlements that sprung up after the quake, down from a peak of 1.3 million, according to the International Organisation for Migration.

"There are still too many tents," Rosalynn Carter said at a news conference.

Families help build the Habitat homes and then live in them rent-free for five years. After that, they will then pay the government about $70 a year. The homes have a small separate space that can be used as a room or closet, and each tenant receives an outdoor latrine and shower. A well is shared.