The Organisation for Economic Co-operation and Development on Tuesday maintained its global economic growth forecast for 2018 as the expansion, though modest, becomes more "synchronized" across countries.

"The broad-based cyclical upturn is set to persist into 2018, with global gross domestic product growth projected to strengthen to 3.7 percent," the OECD said in its economic outlook report. The world economy is expected to register a 3.6 percent increase in 2019.

Lifted by robust exports, Japan's economy is projected to expand 1.2 percent in 2018, unchanged from the OECD's previous forecast in September.