The United Nations Secretary General, Kofi Annan, has visited areas of Niger badly hit by an ongoing food crisis in the West African nation.

Mr Annan met Niger's President Mamadou Tandja in the town of Zinder, where he was greeted by large crowds, and toured a clinic for malnourished children.

The UN says more than 2.5m people, and 32,000 children, have been affected by an acute food shortage

The UN has run an appeal but has been accused of not acting quickly enough.

Less than half the $81m (£45m) called for by the UN has been pledged by international donors, the organisation says.

The BBC's Dan Isaacs in West Africa says Mr Annan's trip is a clear indication that he is intent on addressing the issue of the UN response head-on.

'Hunger, hunger'

Mr Annan met President Tandja at Zinder airport in eastern Niger, one of the areas worst hit by drought and a devastating locust infestation during 2004.

A crowd of about 1,000 greeted him at the airport, some shouting "hunger, hunger" at the visiting dignitaries.

Mr Tandja has denied that Niger is in the grip of a famine, and has criticised the international community and the UN for the way they have handled the escalating crisis.

At the village of Madara, outside Zinder, Mr Annan visited a feeding centre run by Medecins Sans Frontieres (MSF), the organisation which on the eve of his visit issued a stern critique of the UN's effectiveness in Niger.

"I came here to see for myself what is happening and to discuss with the president and the prime minister what we can do together to improve the situation," Mr Annan said.

'Not good enough'

MSF has alleged that UN food relief, provided by the World Food Programme, is poorly targeted and does not deliver enough food to the right place at the right time,

In a statement released on the eve of Mr Annan's visit, MSF said children under five, who were at most risk from malnutrition, were not always getting the aid they needed.

"Neither in quantity or quality, was it [the UN] responding to the gravity of this epidemic of desperate malnutrition," the statement said.

In Madara, Mr Annan praised MSF's work and said he had met mothers and children affected by the food crisis.

On Wednesday, Mr Annan is due to meet Mr Tandja in the capital, Niamey, and attend meetings on food security, development and democracy.

The food emergency follows last year's poor rains and invasions of locusts, who ravaged crops across West Africa.

Harvest hopes

Our correspondent says this is a critical moment for the international relief operation.

The next harvest in Niger is due in October and hundreds of thousands of people are in need of emergency assistance to bridge that gap.

Aid agencies say that this year's rains have been good, raising hopes that the 2005 harvest will be plentiful.

But, longer term, Niger faces profound economic problems and its people live at the very margins of sustainable life, our correspondent says.