The United Nations is scaling up efforts to provide Haitians affected by the January earthquake with at least some forms of shelter before the rainy season comes, the top UN relief official said on Thursday.

"We will make sure that everybody we can reach has ... proper, waterproof, makeshift shelter over their heads by the time the rainy season starts in earnest," Emergency Relief Coordinator John Holmes told a news conference at the UN Headquarters in New York.

Holmes, who is also under-secretary-general for humanitarian affairs, said that about 60 percent of those that need shelter have been provided with tents or tarpaulins, and the aim is to reach everyone with emergency shelter by April 1.

An estimated 1.2 million Haitians need emergency shelter, having been rendered homeless by the Jan. 12 quake which devastated the Caribbean nation.