China said on Thursday it was "normal" to carry out ballistic missile launches, after a US media report accused Beijing of having test-fired an intercontinental weapon last week.

US media site Washington Free Beacon, citing unidentified Pentagon officials, reported that China had carried out a test of its DF-41 long-range missile on April 12.

The report linked the tests to tensions between Washington and Beijing over the South China Sea, noting that it came three days before a visit by US Secretary of Defence Ashton Carter.

The DF-41 missile has a range of some 14,000 kilometres (8,700 miles) and could, according to some experts, carry up to 10 nuclear warheads.

In a brief response, China's defence ministry did not deny a test had been carried out, but dismissed media reports of a specific location as "pure speculation".

"It is normal for us to carry out scientific research tests in our own territory, according to our plans, and they are not aimed at any specific nations or targets," said a statement on its website.

China claims nearly all of the South China Sea, which is home to some of the world's most important shipping lanes and is believed to contain vast oil reserves.

But many of its Southeast Asian neighbours have overlapping claims, and tensions have risen over China's construction of artificial reefs in the disputed waters.

On Monday, China's defence ministry gave its first confirmation that Beijing had landed a military flight on the Fiery Cross reef in the Spratlys archipelago, also claimed by the Philippines.

On the day of Carter's trip, Beijing said that one of its top military officials had visited a South China Sea island.