PORT-AU-PRINCE- Four weeks after an earthquake shattered its capital, Haiti remains in a precarious situation with no clear idea of how to house 1 million people living in the streets, Prime Minister Jean-Max Bellerive said on Tuesday.

Bellerive said it could take his impoverished Caribbean nation three or four years to return to its pre-quake state and up to 10 years to rebuild 250,000 houses destroyed by the magnitude 7 earthquake on Jan. 12.

Planning for shelters and new homes is not far along and the number of spontaneous tent encampments around the city -- where most Haitians are living under plastic tarps or cloth bedsheets -- has grown to nearly 500, Bellerive said.

We are still in a very difficult situation, Bellerive told Reuters. We still don't have a clear vision of certain problems -- how we are going to relocate all those people.

Bellerive, an economist who became prime minister only two months before the quake, said conditions are improving in some areas, with better food distribution and better health services.

Foreign donors have poured millions of dollars worth of food, shelter and other aid into Haiti, where before the quake most people lived on less than $2 a day.

Bellerive said shelter remained the biggest problem for the government to address. Residents whose homes were damaged, or who are afraid to sleep indoors, have set up camp on the edges of the capital's airport, the main city square downtown, a golf course, open fields, courtyards of businesses and sidewalks.

During the next four to six months, he said, the government will have to move people to shelters or establish them in camps with better facilities. Haiti's rainy season could start in weeks, and the Caribbean hurricane season begins on June 1.

In some places they will stay where they are, (we will) just accommodate them. In other places, we just have to move them. And if we move them we have to give them all the services because they won't be in the condition to take care of themselves, Bellerive said.

Sanitation in the camps, most of which have no toilets or running water, is a big concern with the rainy season coming, Bellerive said. The government hopes to have latrines in place before the rain starts and is sending health workers out to counsel residents about the hazards of sleeping, cooking and bathing in the same small spaces.

Although health officials have seen rising cases of tetanus and other ailments, Bellerive said there had been no major outbreaks of disease.

We believe we are controlling any surge of any epidemics in Haiti, he said. We don't have any epidemics in Haiti up until now.

The government has said 250,000 homes were destroyed by the earthquake, most of them in the capital, and thousands more may be declared uninhabitable in the weeks to come. Asked how long it would take to rebuild those homes, Bellerive said: A long time ... I've said 10 years. I say it will be at least three to four years to go back to the 11th of January.

(Editing by Will Dunham)