Natural teak forests in Myanmar and elsewhere are declining and the quality of natural-grown teak wood is deteriorating worldwide, a United Nations report says.

The U.N. Food and Agricultural Organization said natural teak forests declined by 939,000 acres globally between 1992 and 2010, China's official Xinhua news agency reported.

Natural teak forests grow in only four countries in the world, the FAO said -- India, Laos, Myanmar and Thailand.

Myanmar, formerly called Burma, is the only country currently producing quality teak from natural forests, while India, Laos and Thailand have bans on logging in natural forests or on log exports.

In Thailand, a complete ban on logging in natural forests introduced in 1989 has seen recovery of natural teak forests, which have increased by 2.9 million hectares, the FAO reported.

Human-planted teak forests are increasing in area and can produce high quality wood when good management is practiced, the report said.

Planted forests of teak, one of the most important and valuable hardwoods in the world, have attracted large private sector investments in Africa, Asia and Latin America.

"Although the time until trees reach harvestable dimensions is comparatively long and on average takes between 20 and 80 years, teak planting serves local communities as a savings account and in the long run helps smallholders improve their livelihoods," Walter Kollert, FAO forestry officer, said in the report.