Those living in Senegal's poor, cramped suburbs who have no running water at home can pay up to four times more for water than rich households, a United Nations water and sanitation expert said Monday.

UN special envoy Catarina de Albuquerque, speaking to journalists after a seven-day mission in Senegal, urged the west African nation to boost investment in water and sanitation, as current budgetary allocations are "insufficient".

"I noticed that the poorest are forced to pay much more than the better-off for water ... up to four times more," said De Albuquerque, a Portuguese national.

"Some families who fetch their water from street fountains spend up to 20 percent of their monthly income on water services" while the internationally accepted standard is between three and seven percent, she said.

This takes money away from spending on other priorities such as health and education.

She noted however that "considerable efforts" made by Senegal in recent years had allowed the country to provide 87.2 percent of the country with running water in 2010 compared to 69 percent in 2008.

"The Senegalese government has often said that sanitation is a priority but this has not been matched bby sufficient budgetary allocations."

Alhaji Dieng, an official from the Senegalese Water Company said water coverage in urban areas is 98.5 percent, with street fountains providing for 12.2 percent of this figure.

Africa's westernmost state, Senegal is also one of the continent's most stable governments, however poverty is widespread and unemployment hovers at around 48 percent.