SIR - I have joined with the UK's leading aid charities to launch an emergency appeal to save lives in Darfur, Chad and the Central African Republic.

We are seeing one of the greatest concentrations of human suffering right now in Darfur and Chad with 4.5 million people affected.

The impending rains will make the situation worse, bringing the risk of deadly conditions like diarrhoea and malaria, especially for children, pregnant mothers and the elderly. Aid agencies need to bolster life-saving food and medicine stocks before the downpours.

The gathering storms will make the delivery of aid a much more difficult task, with vehicle tracks disappearing and rivers becoming all but impossible to cross.

Money raised will help people affected by the conflict, giving shelter, clean water and sanitation, emergency food and vital items such as water buckets, blankets and soap and enable medical teams to provide emergency care.

To donate to the Darfur and Chad Crisis Appeal you can call 0870 60 60 900, visit www.dec.org.uk or donate at any post office or high street bank. Cheques made payable to Darfur & Chad Crisis can be sent to PO BOX 999, London, EC3A 3AA.

Joanna Lumley, of behalf of Darfur & Chad Crisis Appeal, London