WASHINGTON - China has reportedly tested a new variant of its Dongfeng-5 long-range missile capable of carrying a payload of 10 individual warheads, a Washington-based newspaper reported, citing US defence sources.

The move indicates that China is increasing the number of warheads in its arsenal, the Washington Free Beacon said in its report on Monday (Jan 31).

The test of the DF-5C missile was carried out last month using 10 multiple independently targetable reentry vehicles, or MIRVs, the report said.

The missile was fired from the Taiyuan Space Launch Centre in central China and flew to a desert in western China.

Pentagon spokesman Gary Ross told the Washington Free Beacon the test was monitored.

"The [Defence Department] routinely monitors Chinese military developments and accounts for PLA [People's Liberation Army] capabilities in our defence plans," Commander Ross said.

The paper said the test is significant because it indicates the secretive Chinese military is boosting its nuclear arsenal.

Estimates of China's nuclear arsenal for decades put the number of strategic warheads at the relatively low level of around 250 warheads.

Uploading Chinese missiles from single or triple warhead configurations to up to 10 warheads means the number of warheads stockpiled is orders of magnitude larger than the 250 estimate, said the Washington paper.

A Chinese military expert from an institute affiliated with the PLA said a new test would not have been aimed at new US President Donald Trump, who has raised tensions with China through vocal criticisms of Beijing.

"The test of a nuclear missile requires permission from the highest level - the Central Military Commission. It takes at least one year for the military to get the approval and to prepare for it," said the expert, who refused to be named due to the sensitivity of the matter.

"It is not a random decision to be made just because Trump is now in office," the expert said.