Military-ruled Myanmar plans to sell more than 1,300 lots of jade and gems this week in an auction that has become an important source of revenue for the junta, official media said Tuesday.

The sale will include 312 lots of gems and 1,029 lots of jade, apparently making it about half the size of the last sale in July, the New Light of Myanmar newspaper said.

The 890 buyers — including 335 foreigners — have been viewing the lots since Monday and sales start Thursday, the newspaper said.

Myanmar used to hold gem and jade auctions once or twice a year but they have been taking place with increasing frequency, providing the cash-strapped junta with much-needed foreign income.

The next one is already set for October and the government has threatened to punish mining companies by limiting their exploration work in the future if they fail to bring enough jade and precious stones to the sale.

July’s auction was the biggest ever, with 2,300 lots of jade being sold to merchants including 1,450 foreigners.

The junta has been reluctant to say how much it earns from the auctions but estimates run into tens of millions of dollars.

Myanmar is one of the world’s poorest nations and is subject to US and European economic sanctions because of human rights abuses and the house arrest of democracy leader Aung San Suu Kyi.

The impact of the sanctions has been weakened, however, by the eagerness of neighboring China, India and Thailand to tap Myanmar’s vast natural wealth to fuel their own growing economies.

Myanmar can boast of significant natural gas and mineral resources, as well as highly-prized teak. The timber often disappears onto the black market which is estimated to be at least half the size of the formal economy.