Villegas said that under the contract, which calls for Bolivia to pipe 27 million cubic metres per day of natural gas to its southern neighbour, the hydrocarbons-rich nation can delay the start of exports for a year.

"The contract establishes that starting 2010 we have to deliver 27 MMcm, but we can delay that by one year and we expect to (start exports) by 2011," Villegas said at a meeting with reporters and analysts.

"But we may have the necessary export volume by 2010."

Bolivia currently produces about 40 MMcmd., selling about 7.7 MMcmd to Argentina and 30 MMcmd to Brazil.

But analysts told Reuters Bolivia's leftist government may struggle to double natural gas output to meet export and internal targets after President Evo Morales announced the nationalisation of the energy industry in the impoverished country last year.

Investors including Brazil's Petrobras, Spain's Repsol YPF and France's Total are negotiating with the government over investment plans to be presented by the end of the year.

Morales says companies that do not invest will be thrown out, and analysts say the new terms, which cut the returns of foreign operators in Bolivia, may damp interest.

Villegas said that he has been meeting with foreign energy companies to set the amount of investment for 2008, but the figures had not been finalised.

"I don't have a number, I believe we are going to have that number by mid-December but I know there is willingness by the companies including Petrobras," he said.

Brazil's state oil company, Petrobras, had previously said it will invest only enough to maintain its current operations.

Published: 16 October 2007 17:03 GMT  | Last updated: 16 October 2007 17:17 GMT