It also upgraded Mongolia's growth in 2019 to 6.1 percent from 4.3 percent, according to an update of ADB's flagship annual economic report, Asian Development Outlook 2018.

Mining investment will continue but a slowdown in the growth of mining investment, however, is expected to temper growth of Mongolia's gross domestic product (GDP) in 2019, it said.

"Mongolia's economy has performed better than expected in 2018. This upward revision is based on better performance of coal exports and stronger-than-expected private consumption," Yolanda Fernandez Lommen, ADB country director for Mongolia, said at a press conference.

"Mongolia's economy posted strong growth in the first half of this year at 6.3 percent, continuing the strong economic performance of 2017. Private consumption has been higher than anticipated due to a surge in credit to households," she said.

"Also, external demand for Mongolian coal has boosted economic performance and increased revenues, while investment into the mining sector continues to play a key role," she added.

According to the ADB, investment remained the main source of Mongolia's economic growth in the first half of 2018, contributing 12.6 percentage points to its GDP.

ADB, based in the Philippine capital Manila, is dedicated to reducing poverty in Asia through inclusive and environmentally sustainable economic growth, and regional integration.

Established in 1966, ADB has 67 members, including 48 from within the Asia-Pacific region. In 2017, the bank's operations totaled 32.2 billion U.S. dollars.