* U.N. shuts down West Africa humanitarian flights
* Shortage of funds to blame
(Adds comments on financial crisis, paragraphs 6-8)
GENEVA, March 17 (Reuters) - The United Nations will shut down its humanitarian air services in much of West Africa because of a shortage of funds, a spokeswoman said on Tuesday.
Emilia Casella of the World Food Programme (WFP) said the chartered aircraft used to ferry aid workers and supplies to remote parts of Guinea, Sierra Leone, Liberia and the Ivory Coast would stop on Friday, March 20.
"In areas that are not reachable by land ... aid workers will not be able to reach vulnerable people with medical care, food, water and sanitation, and other crucial services," she told a news briefing in Geneva.
"The U.N. will also not be in a position to carry out timely medical and security evacuations of humanitarian personnel, if and when needed," the spokeswoman said.
There are 250 humanitarian agencies now working in the affected West African countries, Casella said. The exact number of people receiving help from the U.N. air service was not known, but thousands of people would be affected, she said.
The suspension follows the halting of air deliveries to Niger in February, and temporary shutdowns of flights to the Central African Republic, Niger, and Sudan last year because of budget constraints that aid groups fear will worsen this year as the world’s recession bites government budgets.
Casella said the U.N. air service had faced "chronic underfunding problems for years," making the prospect of aid cuts in response to economic pressures a real worry for the programme that brings assistance to hard-to-reach people.
"We are concerned that there is a risk that donors will find it difficult to maintain their contributions," she said, while stressing that funding levels had not fallen to date.
Donor funds from the European Union, United States, Britain, Canada, Spain and the Netherlands amounted to $115 million last year, far below the $193 million budgeted for the flights, which cut days off the time needed to get help to the needy.
Aid workers in West Africa have said they will have extreme difficulty doing their work without the helicopters and aircraft to help them reach places where roads and bridges are impassable or where security problems make road journeys unsafe.
Ron Redmond, a spokesman for the U.N. High Commissioner for Refugees (UNHCR), said the flights were crucial for reaching people displaced by conflict and disasters.
"We work at the end of the earth and the only way to get there is on the humanitarian air service," he said.
Worldwide, the U.N. air service last year carried 15,000 tonnes of humanitarian cargo and 360,000 U.N. staff, aid workers, donors and media staff. The 58 helicopters and aeroplanes also carried out medical and security evacuations in Chad, Mozambique, Myanmar, Somalia and Sudan. (Reporting by Laura MacInnis; editing by Stephanie Nebehay and Giles Elgood)