After showing signs of fever and pneumonia, Lai was hospitalized in critical condition on April 1. Those who had close contact with him have been put under observation, but none have so far shown any signs of infection.

Meanwhile:

-- Sudan has reported its first incidents of avian influenza infection in poultry, the country's Ministry of Animal Resources announced Tuesday.

Ahammed Mustafa, under secretary at the ministry, told reporters: "Laboratorial tests have confirmed the existence of bird flu cases in Khartoum and Jazeera.

"Until now, the health authorities have culled more than 100,000 chickens at 15 farms in Khartoum."

-- Workers at a Pakistani poultry farm where avian influenza was discovered have been tested for the disease and appear to be uninfected.

Khaleej Times Online quoted Dr. Muhammad Afzal, commissioner of livestock and animal husbandry, as saying: "Medical reports of all the four men at the affected farm are negative but they are still under observation."

-- Nigerian authorities reported a fresh case of avian influenza in the country's poultry Monday.

The official News Agency of Nigeria reported Monday that there had been an outbreak of bird flu in Bakori and Jargaba towns in the northern state of Katsina, killing 200 birds.

Alhaji Halliru Atiku, head of agriculture in local government, said the local authorities had supplied disinfectant and special chemicals to the region's poultry farms in response to the outbreak.

-- In England, a dead duck and sick swan found in Merseyside, in the northwest of the country, on Sunday afternoon, have sparked the country's first avian flu alert.

Tests on the birds are currently being conducted, with results expected Wednesday.

A spokesman for the Department of Environmental, Food and Rural Affairs said the tests were being conducted as a matter of course, and as the only other case of avian influenza in the British Isles had been far to the north, in Scotland, there was no need for concern.

Defra tests suspicious birds as a matter of course, the spokesman said, and only reports positive diagnoses to the public.

-- McDonald's has asked its European suppliers to bring free-range birds indoors to guard against consumer concerns of contracting avian influenza, although there is no risk of contracting bird flu from cooked poultry or eggs.

Catherine Adams, vice-president of worldwide quality at McDonald's, was quoted by Australia's The Age as saying: "We are now imposing standards which require that those free-range chickens that are producing free-range eggs be brought into houses because of the threat of the spread of avian influenza."

While the move is designed to inspire consumer confidence, there are concerns that when multinational corporations such as McDonald's begin such maneuvers, customers may incorrectly assume that there are risks to be had in consuming cooked eggs and poultry that have been reared outdoors, which is not the case at all.

"These are the first uncovered walls of the pyramid," said Osmanagic, who studied Latin-American pyramids for 15 years and who proposed the theory that the 650m mound rising above the small town of Visoko is actually a step pyramid -- the first such found in Europe.

"We can see the surface is perfectly flat. This is the crucial material proof that we are talking pyramids," he said.

The huge stone blocks appear to be cut in cubes and polished.

"It is so obvious that the top of the blocks, the surface is man-made," Osmanagic said. He plans to continue the works throughout the summer, "after which the pyramid will be visible", he said.

The research on the hill, known as Visocica, found that it has perfectly shaped, 45-degree slopes pointing toward the cardinal points, and a flat top. Under layers of dirt, workers discovered a paved entrance plateau, entrances to tunnels and large stone blocks that might be part of a pyramid's outer surface.

Satellite photographs and thermal imaging revealed two other, smaller pyramid-shaped hills in the Visoko valley.

Last week's excavations began with a team of rescue workers from a nearby coal mine being sent into a tunnel believed to be part of an underground network connecting three pyramidal-shaped hills.

They were followed by archaeologists, geologists and other experts who emerged from the tunnel later to declare that it was certainly man-made.

The work will continue for about six months at the site just outside Visoko, about 30km north-west of the capital, Sarajevo. Two experts from Egypt are due to join the team in mid-May.

"It will be a very exciting archaeological spring and summer," Osmanagic said. -- Sapa-AP