ABIDJAN, Ivory Coast (AP) _ Severe diarrhea has hit some of the thousands of exhausted refugees on board a leaky ship that set sail from Liberia a week ago and medical officials fear it could be a symptom of cholera.

``We can expect very serious consequences from diarrheal disease,'' Phil Doherty of the relief agency Doctors Without Borders said today.

Making matters worse, officials in Ghana said today that some of the 3,000 to 4,000 refugees aboard the Bulk Challenge may not be allowed to leave the boat when it arrives in the capital of the West African country sometime over the weekend.

The ship may be forced to turn around and head back to Liberia. It has already been turned away from the Ivory Coast.

Ghanian Foreign Minister Obed Asamoah said there would be ``no wholesale acceptance'' of the refugees. He said Ghanaian authorities would board the boat to screen refugees for medical needs and they would be given assistance before being put back on the boat. He also said Ghanians, foreigners and Liberian workers for United Nation's and non-government relief agencies would be allowed to remain in Ghana.

Like the Ivorian authorities who turned away the ship on Thursday night, Asamoah expressed concern that many of the refugees on the Bulk Challenge had been combatants in the monthlong battle that has destroyed the Liberian capital, Monrovia.

``We don't want to take any more refugees,'' Asamoah told the Ghana News Agency. ``We have had enough refugees. Especially we don't want those who are combatants.''

Doherty said Doctors Without Borders had sent a small boat to follow the Bulk Challenge to Ghana, with a doctor and nurse on board.

He said there was little water or food on board and only one toilet available for the refugees who have been forced to sleep on top of one another.

``It's not going to get better and the worst-affected people will be malnourished and generally weakened,'' Doherty said. ``If there is cholera on board, under those circumstances, those people have a very poor expectancy.''

Panicked Liberians fleeing a month of brutal fighting in Monrovia packed the Ghana-bound freighter last Sunday.

The ship limped into San Pedro in western Ivory Coast on Monday, having taken on 6 feet of water. Some repairs were made Thursday, but it was unclear whether the boat was seaworthy when it set sail for Ghana later that day.

Ivory Coast officials forced the ship back into the Atlantic Ocean Thursday night. The country is already was flooded with 350,000 Liberian refugees who have fled across the border since warlord Charles Taylor launched the war from Ivory Coast six years ago.

Meanwhile, in Liberia, tens of thousands of people continued to flee the capital to the countryside, despite several days of relative calm in Monrovia.

There was sporadic gunfire on the streets today but a call for an immediate cease-fire by West African leaders earlier this week appears to have been heeded for now.

More than 150,000 Liberians have died in six years of civil war, half the population of 2.9 million has been left homeless, and a half-dozen warring factions have emerged.