The economy of China's Hong Kong Special Administrative Region will grow 2.5 percent this year, the Asian Development Bank (ADB) forecast on Wednesday.

The forecast is lower than the growth at 3 percent in 2018, mainly because of the global cycle, ADB Chief Economist Yasuyuki Sawada said while delivering the bank's annual publication Asian Development Outlook.

Hong Kong's economic growth rate will be 2.5 percent in 2020, according to the ADB report.

Despite increasing headwind, Asia's growth slowed slightly from 6.2 percent in 2017 to 5.9 percent in 2018, as global trade and economic activities decelerated at the end of the year, affecting many economies in the region, according to the report.