China's foreign exchange reserves increased for the sixth consecutive month in January to a new decade high, official data showed.

The reserves rose to $3.3991 trillion as of the end of January, up 1.23 percent or $41.2 billion, from the previous month, the State Administration of Foreign Exchange said on Saturday.

The $3.3991 trillion in reserves marked the highest level since November 2015, when the reading came in at $3.44 trillion, according to official data compiled by market tracker Wind Info.

SAFE said the country's foreign exchange reserves increased last month amid a declining US dollar index and rising global financial markets, with China's improving economic fundamentals conducive to keeping foreign exchange reserves generally stable.