Martin Dawes reports from southern Sudan where many people are still dying

The medical charity, Medecins Sans Frontieres, says not enough food is being delivered and as a result people are dying and children in feeding centres are not gaining weight.

Children are dying from starvation as well as illness

One of the charity's aid workers Simone Von Den Berg, in the war-torn state of Bahr Al Ghazal, said: "I've been here two weeks and I haven't seen any improvements because there is no more food in the area yet."

The food crisis, which was first predicted late last year, has been a result of both drought and civil war.

Although huge resources have been brought in, many emergency food supplies have arrived too late for many people.

Desperation takes its toll on some aid workers

"The needs are growing we are definitely going to need more food," said David Fletcher from UN Operation Lifeline Sudan. "Even at current rates the food we have we run out in the middle of July and we know the needs are going to continue long after that."

Marie Staunton says food supplies will not cover the rising number of people starving

Marie Staunton, deputy director of Unicef UK, was also worried about the escalating problem.

She said: "The position is that we do have food supplies until September but that is if the situation doesn't get worse. And from thinking 350,000 people were at risk in April we now know it's nearly a million people."

"We are getting the flights in, we are able to deliver food but the other problem we're finding is that food alone isn't enough to cure sick children. We also need to get in the vaccines because children are dying of diarrhoea and even measles."

Fighting continues

Meanwhile, the Sudanese government has been condemned for hiring 2,000 convicted criminals for $1,000 a head from China to fight alongside its forces, according to the opposition group, the National Democratic Alliance.

The secretary-general of the National Democratic Alliance, Mubarak al-Mahdi, was quoted as saying the government's move was "a criminal act" and called on the Chinese government to stop intervening in Sudan's internal affairs.

Last week, rebels of the Sudan People's Liberation Army (SPLA) said they had killed or wounded 300 government solders.

Sudan has been hit by outbreaks of civil war for over 40 years, but the current phase of the conflict began in 1983.

The black, mainly Christian or animist south is fighting for autonomy from the Muslim north.