CARACAS (Reuters) -- Venezuela and Colombia on Saturday began construction of a gas pipeline linking the two countries, another step in Venezuelan President Hugo Chavez's efforts to promote Latin American energy integration.

Venezuela, the world's No. 5 oil exporter, is seeking to reduce dependence on U.S. energy markets as part of a self-styled socialist revolution that promises to end poverty and unite Latin American nations.

Chavez and Colombian President Alvaro Uribe held a ceremony in western Venezuela to solder the first pipe of a 225 kilometer (140 mile) gas pipeline, projected to cost $335 million, linking Venezuela with Colombian gas fields.

"The axis that will be formed with this pipe ... should be like a central nerve for the integration of Colombia and Venezuela," Chavez said in a speech.

The pipeline, expected to be completed by next March, will send around 150 million cubic feet per day of gas from the Punta Ballenas fields in Colombia to the chronically gas-deficient areas of western Venezuela.

Within an estimated four to seven years, when Colombia's fields dry up and Venezuela's gas transport systems have been expanded, the pipeline will reverse flow to send around 200 million cubic feet per day of gas to Colombia.

Panamanian President Martin Torrijos was also present at the ceremony, since Colombia and Venezuela are seeking to expand the project to supply gas to Panama.

Chavez is leading an effort to build a massive gas pipeline stretching from Venezuela to Argentina with an estimated price tag of $20 billion.

A project to export liquid natural gas to the United States has been delayed by several years, and Chavez has said Venezuela will supply Latin American countries before developing export plans to the United States.

Venezuela produces around 6.3 billion cubic feet per day of natural gas, most of which is used by the nation's oil industry operations.

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