Wed Apr 22, 2015 4:31pm BST

More than 100,000 people in Vanuatu have no clean drinking water, a month after a monster cyclone struck the tiny Pacific nation, the United Nations Children's Fund (UNICEF) said on Wednesday.

Two thirds of the archipelago's water and sanitation infrastructure has been damaged or destroyed and most wells are contaminated, UNICEF said in a statement.

"There is water but quality is not that good because of the contamination," Ketsamay Rajphangthong, chief of UNICEF Vanuatu field office, told the Thomson Reuters Foundation in a phone interview from Vanuatu.

"When the water is contaminated there's lots of risks coming after that, especially diarrhea and also other forms of disease."

Tropical Cyclone Pam destroyed homes and infrastructure when it swept across the South Pacific island nation on March 13, leaving 11 dead and affecting the majority of the 252,800 Vanuatu population.

Seventy percent of wells have been contaminated and bacteriological tests showed that water required purification before drinking at all sites tested outside the capital Port Vila, UNICEF said.

The agency has been providing water purification tablets and plastic sheets for rainwater collection as a temporary substitute for the 68 percent of rainwater harvesting structures that have been damaged by the cyclone.

Cyclone damage means that women and children have to walk to shower facilities and toilets further from home, or defecate in the open, lacking privacy and exposing themselves to abuse, said Rajphangthong.

UNICEF needs $1.5 million to close the gap between donations and its appeal target, she said.

"We are still trying to talk to donors and different governments so we can get the additional funds so we can really finish the renovation of (damaged) facilities because this is very urgent," she said.

"We have been supporting the government and working with other U.N. agencies and NGOs to make sure that we assess the damage and try to help the people to get back to their lives as soon as possible," she added.

On Tuesday the United Nations Development Programme launched a cash-for-work debris removal project to provide short-term jobs for up to 100 of the most vulnerable people in cyclone-affected communities.