WASHINGTON, Jan 21 (Reuters) - U.S. Treasury Secretary Janet Yellen said on Friday she believes the economic forces that have keep interest rates low in recent decades will continue after the COVID-19 pandemic ends, helping to keep the U.S. debt burden manageable.

Yellen told a World Economic Forum virtual session that while the debt-to-GDP ratio is higher than in the past, the interest burden "is very manageable."

The Biden administration's fiscal policies that pair further spending plans with tax increases are "designed to make sure that those interest payments remain manageable and the debt to GDP stabilizes at manageable levels on a long-term basis." (Reporting by David Lawder and Andrea Shalal)