About five per cent of the world's maritime commerce moves through the Panama canal [EPA]

Flooding has forced the closure of the Panama Canal for the first time in 21 years and heavy rains were being blamed for at least eight deaths in the Central American country.

More than a thousand people in Panama were evacuated on Wednesday because of what authorities called historic flooding caused by record rainfall.

Ricardo Martinelli, president of Panama, said it was the first time the canal was closed because of weather since it opened in 1914.

"Our meteorologists say it's never rained so much in Panama in the 73 years that we've kept climate records," Martinelli said. He said eight people were dead.

The last time the canal closed was on December 20 1989, when US troops invaded the country to topple president Manuel Noriega.

The country's Civil Protection System put eastern Panama on high alert and issued evacuation orders for about 1,500 people in dozens of flooded neighbourhoods.

Authorities recovered the bodies of two girls who were on a boat that capsized in the town of Chepo in the southeast part of the country. The other deaths were reported in the Colon province.

About 50 people in two communities were ordered to leave their homes and residents near the Chagres river were told to be on alert.

The canal was closed after water overflowed the banks of lakes Gatun and Alajuela, which supply the canal. Authorities said they've opened the floodgates for both lakes.

"We're taking measures to normalise transit operations in the coming hours," Manuel Benitez, the executive vice president of canal operations, said on Wednesday afternoon.

Last year, work began on a $5.2bn project to enlarge the canal by constructing a third set of locks to ensure that today's super-size container ships, cruise liners and oil tankers - many of which are too wide for the canal - will be able to navigate the waterway in the future.

The work should be completed by August 2014, a century after the canal's inauguration.

The third set of locks, parallel to the existing two, would accommodate massive vessels 366 metres in length, 49 metres wide and with a 15-metre draft.

About five per cent of the world's maritime commerce moves through the canal, and the US is its main user.

Meteorologists say the heavy rains are part of the La Nina weather phenomenon.

Source: Agencies