Soldiers have been sent to northern Myanmar to protect an enormous jade boulder that could weigh up to 50 tonnes.

The top minister in Kachin state, Lajun Ngan Seng, says the raw jade was discovered in the mining region known as Hpakant just over a week ago.

Still half buried, it's difficult to know its exact size.

But he says authorities believe it may be 5.5 metres high, weighing up to 50 tonnes.

Myanmar is one of the world's biggest producers of jade, most found in the conflict-torn mountains of Kachin, where ethnic rebels have been fighting the government for more than half a century.

Most of the gemstones, considered to be of the highest quality, are smuggled over the border to China.