Miners in Myanmar have unearthed a 175-tonne jade boulder worth an estimated US$170 million (S$236 million).

The boulder, 4.3m high and 5.8m long, was found in a mine in jade-producing Kachin state, in the north of the country, media outlets reported.

The rock is second in size only to the carved statue at the Jade Buddha Palace in China, which weighs 260 tonnes, Britain's Mirror Online reported.

"We thought we had won the lottery. But this belongs to the country. It is in honour of our leaders," the Mirror Online quoted miner Sao Min, 44, as saying.

Media said the boulder will be sent to China to be made into jewellery and sculptures. Myanmar is the source of most of the world's finest jadeite, while China is the world's largest market for the gemstone.

Myanmar's multibillion-dollar jade industry has been criticised for being dangerous and poorly regulated.

Landslides are a regular hazard as mainly itinerant workers pick through piles of waste left by large-scale industrial mining firms. Last year, more than 100 people were killed in a landslide at a mining site in Kachin.