The US military and intelligence officials say that China has developed the new long range Dongfeng-41 ICBM with mobile launching system making it harder to find and destroy the missile before it is launched, the New York Times said.
But the Global Times - a newspaper controlled by China's Communist Party - disputed Western media reports of Dongfeng-41 tests being carried out last month.
It admitted China was developing the capability to put multiple warheads on its inter-continental ballistic missiles.
The new generation Dongfeng-41 is estimated to have a strike distance of 12,000 to 14,000 kilometers and armed with single, 3, 6, or even 10 multiple independently targetable re-entry vehicle (MIRV) warheads.
The NYT, quoting a Congressional panel, said that US and other western powers might have underestimated the size of China's nuclear arsenal, suggesting that the new reports say that it currently had 55 to 65 ICBM.
The US experts also said that Beijing had separately tested Submarine launched missiles in recent weeks, which it could use to outflank American missile defence systems.
The experts also said that China had developed the expertise to mount dummy warheads on some of its nuclear missiles and that these have heat and electromagnetic devices designed to trick defence missile system.
The NYT also said that China was preparing two Submarines for deployment each with 12 missiles.
US experts said China's moves to modernise its missiles comes in the wake of it carrying out sea trials of its first aircraft carrier and flight test of its new stealth J-20 jet.
Th NYT said to counter the Chinese build up, US was considering placing additional high-tech radar systems to track Chinese ballistic missiles either in southern Japan or in south east Asia.
The Economic Times