MANAGUA, Nicaragua (AP) - In a matter of weeks, a little-known Chinese tycoon has hired some of the world's top experts in mammoth infrastructure projects and pushed through Nicaragua's congress a bill granting him the exclusive right to develop a multibillion-dollar rival to the Panama Canal.

Now, the real work begins.

Thursday's vote may have given Mr Wang Jing the concession to build a canal across this Central American nation, but his HK Nicaragua Canal Development Investment Co. still has to study whether the idea is truly economically viable.

Spokesmen hired by the company say they believe that rising world trade means it is highly likely that a new canal could be profitable. Yet they acknowledge that what will be a months-long feasibility study could prove just the opposite.

The project has generated deep scepticism among independent shipping experts. At the same time, environmentalists are worried about the impact on Lake Nicaragua, the country's primary source of fresh water.

The legislation approved by a 61-25 vote in the National Assembly dominated by President Daniel Ortega's Sandinista Front contains no specific route for the canal and virtually no details of its financing or economic viability.

It simply grants the Hong Kong-based company 50 years of exclusive rights to study the plan and build and operate a canal in exchange for Nicaragua receiving a minority share of any profits.

Mr Ortega's backers say the Chinese will transform one of the region's poorest countries by turning a centuries-old dream of a Nicaraguan canal linking the Pacific and Caribbean into reality. They say it will create tens of thousands of jobs for the country and fuel an economic boom that would mimic the prosperity of nearby Panama and its US-built canal.

"One of Nicaragua's great riches is its geographic position. That's why this idea has always been around," Sandinista congressman Jacinto Suarez said during debate on Thursday. "Global trade demands that this canal is built because it's necessary. The data show that maritime transport is constantly growing and that makes this feasible. Opposing it is unpatriotic."

However, Mr Bill Wild, chief project adviser for HK Nicaragua, said a detailed study is needed to determine if a canal would provide enough profit to attract the international investors who will be needed to finance the project.

"There's a compelling commercial reason to build the canal," he said. "We have to prove now that the actual rate of return that the investors will get is adequate."

Mr Wild, who is one of a number of Western experts hired by HK Nicaragua to provide advice ranging from engineering and environmental planning to public relations, also added it was too early to say if a widely-reported project cost of US$40 billion (S$49.7 billion) was accurate.

There are serious questions about whether there will be enough increase in shipping between Asia and the Western Hemisphere to justify a new canal, experts said.

North American companies are increasingly looking to factories and suppliers in the United States and Latin America rather than in Asia, where rising salaries in China are making manufacturing less appealing for foreign companies.

In addition, the global economic slowdown of recent years has resulted in large numbers of ships sitting unused, perhaps 5 per cent of the global fleet. Many vessels are scheduled to be completed in coming years, and the percentage of idled ships could grow to more than 20 per cent, experts said.

Global warming means that even the Arctic may become a viable alternative to crossing Central America by canal.

"Looking at the changing flows and where the growth is in the world economy, personally, I'm not seeing it. I wouldn't invest my money in it," said Ms Rosalyn Wilson, a senior business analyst at Delcan Corp., a Toronto-based transportation consultancy and author of the US logistics industry's annual report.

"It's addressing a need that definitely is not here now, and I'm not sure if it's a 'Build it and they will come' sort of thing," she said.

Mr Paul Bingham, head of economic analysis at the engineering planning firm CDM Smith, which specialises in large water and transportation infrastructure, had similar concerns.

"There's going to be some growth in world trade. The big question is: What routes is that trade going to move on? That's the real challenge that Nicaragua faces," he said. "It's very easy to say trade is going to grow, but that doesn't mean that Nicaragua is going to be in a competitive position to take advantage of it... I'm not convinced right now."

Backers of previous proposals for a Nicaragua canal have argued that the route would prove more economical than Panama's more than century-old canal because it could handle ships with far larger cargo capacity.

But the Nicaraguan path would have to be roughly three times the length of the Panama Canal's 80 km, meaning a much longer passage since ships cannot sail fast in a canal.

The Panama Canal's administrator, Mr Jorge Quijano, said that "gives us even more of a competitive advantage". Environmental effects will also be an issue.

While almost nothing has been revealed about the canal's route, it would certainly cross Nicaragua's biggest source of fresh water, Lake Nicaragua, which is also known as Cocibolca. The water used by the canal's locks could seriously deplete the lake, environmentalists say.

"We're at a crossroads because either you use Lake Cocibolca for floating boats or you use it for drinking water, but you can't use it for both things at once," said Mr Victor Campos, assistant director of the Humboldt Centre, an environmental organisation.

Business analyst Wilson said the use of the lake's water also raises questions for Nicaragua's economy.

"It takes a lot of water to run locks," she said. "Is it going to be done in such a way that's not trading away another part of the country's economy down the line?"