A gas platform has sunk in the Caribbean Sea off the coast of Venezuela, but the energy minister says it poses no risk to the environment.

President Hugo Chavez announced the incident via his account on the social networking site Twitter.

He said all 95 workers were evacuated from the Aban Pearl platform before it sank in the early hours of Thursday.

The rig was at the centre of Venezuela's efforts to develop its huge offshore gas deposits.

Venezuela's energy and oil minister, Rafael Ramirez, said there had been a problem with the flotation system of the semi-submersible platform, causing it to keel over and sink.

But he said a tube connecting the rig to the gas field had been disconnected and safety valves activated, so there no risk of any gas leak.

The Aban Pearl platform was drilling in the Mariscal Sucre offshore natural gas project, off the coast of Venezuela's Sucre state.

It belongs to an Indian company, Aban Offshore Ltd, but was being operated by Venezuela's state oil company, PDVSA, which is developing the field.

Massive reserves

Last week Mr Ramirez stood atop the rig on live television as its gas flare was lit to inaugurate the project.

Venezuela has massive offshore gas reserves, but it has struggled to attract foreign investment, and industry experts say progress has been slow.

President Chavez used Twitter to send out the news of the sinking at just after 0300 local time (0730 GMT).

"I'm afraid to inform you that gas platform Aban Pearl sank a few moments ago. The good news is that 95 workers are safe," he tweeted.

"They were evacuated and at the moment two Navy patrols are moving to the area."

The captain and two other crew stayed on board until it was clear the rig was going down, officials said.

The incident comes less than a month after an explosion that destroyed the Deepwater Horizon rig in the Gulf of Mexico.

Work is still under way to stop a massive oil leak that is threatening the Gulf coast of the United States.