UNITED NATIONS, March 27 (Xinhua) -- The first of three planeloads of the UN Refugee Agency (UNHCR) aid for people affected by Cyclone Idai landed in Mozambique's capital, Maputo, on Wednesday, a UN spokesman said.

"The supplies, including tents, sleeping mats, mosquito nets and solar lanterns, will be distributed to 30,000 people in Mozambique, Malawi and Zimbabwe," said Stephane Dujarric, spokesman for UN Secretary-General Antonio Guterres. "UNHCR's emergency teams are being deployed to all three countries to support the response."

"For its part, the World Health Organization (WHO) is providing supplies to treat diarrheal diseases and cholera and it is helping to set up three cholera treatment centers," Dujarric said. "WHO is also putting together a surge team, to send to Mozambique, of more than 40 people with expertise in logistics, epidemiology and outbreak prevention and response."

The UN Children's Fund (UNICEF) reported that children accounted for more than half of the estimated 3 million people hit by the cyclone across the three countries who "urgently need humanitarian assistance."

"The massive scale of the devastation wrought by Cyclone Idai is becoming clearer by the day," said UNICEF Executive Director Henrietta Fore who visited storm-ravaged Beira in Mozambique. "The lives of millions of children and families are on the line, and we urgently need to mount a rapid and effective humanitarian response across all three countries."

A 281.7-million-U.S. dollar emergency appeal to aid the victims was launched earlier this week.

The situation on the ground is expected to get worse before it gets better as more cyclone-affected areas become accessible, UNICEF said.

"Current conditions -- stagnant waters, lack of hygiene, decomposing bodies, overcrowding in temporary shelters, can easily lead to outbreaks of diarrhea, malaria and cholera -- to which children are especially vulnerable," it said.

The UN children's agency said that it is also "deeply concerned about the safety and well-being of women and children ... in temporary shelters and at risk of violence and abuse, as well as children who have been orphaned or separated from their families because of the storm."

The UN's World Food Programme said that since the cyclone hit it has provided food assistance for more than 150,000 people, and intends to reach half a million in the coming weeks.

Two other flights are scheduled to arrive in Zimbabwe and Malawi this week.