The new locks would be almost 180 feet wide, to allow passage of ''Post-Panamax" ships carrying 8,000 containers.
The government argues that the wider locks are key to protecting the role of the Panama Canal and its crucial income-generating capacity -- an argument President Martin Torrijos was expected to make last night in a nationally televised appeal to voters.
Some 13,000 ships passed through the waterway in 2005, paying about $1.2 billion for canal fees and maintenance and other related services.
Still, the project's estimated $6 billion cost would be a big investment for a country whose government budget is $6.5 billion a year. Officials are counting on private bank financing.
Opponents say the expansion is unnecessary and risky because it depends on variables like the growth of maritime trade and the world economy. They say there are only about 300 of the mammoth ships in operation and their trade routes are mostly within the Pacific.
''Our most important natural resource is not the canal, but our geographic position," former canal administrator Fernando Manfredo said.
Manfredo heads a group that is arguing for a $600 million megaport to be built at the Pacific end of the canal. It would allow the bigger ships to transfer loads to smaller vessels for carrying through the canal to Atlantic ports.
