NAIROBI, May 2 (Xinhua) -- Kenya plans to construct 100,000 "social houses" in the next four years as part of plans to eradicate slums in the country, a housing official said on Thursday.

Patrick Bucha, housing secretary at the Ministry of Transport, Infrastructure Housing, Urban Development and Public Works, said in Nairobi that the houses will be built across the 47 counties.

"The social houses will be for workers in the informal sector who will not qualify for the affordable housing scheme," Bucha said.

As part of the country's national development blueprint, the Big Four agenda, the east African nation plans to build 500,000 affordable houses by the year 2022.

The real estate sector largely constructs houses for the middle- and high-income segment because that is currently the most profitable sector of the industry, Bucha said.

High cost of land in urban areas has pushed the price of owning houses beyond the reach of low-income workers, he said.

The government has mapped 498 informal settlements in all the urban centers of the country, Bucha said.

Beneficiaries of the social houses will be selected from the most needy cases because demand for houses will exceed supply, he said.

To make the houses more affordable, the monthly mortgages will be as low as 20 U.S. dollars a month, Bucha said.