U.S. oil and gas major Chevron Corp. has put all of its Myanmar gas block stakes up for sale, which at a combined likely valuation of $1.3 billion, would be the biggest deal involving Myanmar assets to date, financial sources familiar with the matter said.

The sale, part of Chevron's efforts to preserve cash and retreat from non-core assets in the wake of sliding oil prices, is seen as setting the tone for future deals in a country that is opening up for business after historic elections last year.

San Ramon, California-based Chevron is working with a U.S investment bank on the deal, the sources said, declining to be identified as the sale process has not been made public.

Chevron, which has been operating in Myanmar for about two decades, declined to comment.

It owns 28.3 percent of the Yadana and Sein gas fields operated by France's Total SA in the Andaman Sea, which mostly supplies Thai power plants and also has a stake in the pipeline company that transports the gas to the Thai border. Some of the gas is also supplied to Myanmar.

In addition, it has a 99 percent stake in exploration Block A5 in the promising Rakhine Basin, an area where Woodside Petroleum has recently discovered gas.

Chevron's net daily natural gas production in Myanmar last year averaged 117 million cubic feet.

Chevron is also seeking buyers for its Asian geothermal energy blocks valued at about $3 billion, sources familiar with matter have said.