Updated

South Korea has asked China whether it is the source of a sophisticated missile carrier displayed by North Korea during a military parade last weekend, a Seoul official said.

Military experts have pointed to China as the probable supplier of the 16-wheel truck, but China has denied it. U.N. Security Council resolutions ban countries from supplying arms-related materials to North Korea.

North Korea used the vehicle to unveil a new long-range missile during last Sunday's celebrations marking the centennial of the birth of its late founder, Kim Il Sung. Two days earlier, North Korea launched a long-range rocket but said it failed to put a satellite in orbit.

Seoul was checking whether China, North Korea's only major ally, was the missile carrier provider, a South Korean Foreign Ministry official said Friday, speaking on condition of anonymity, citing the diplomatic sensitivity of the issue.

On Thursday, China denied any wrongdoing in connection with the vehicle's appearance at the North Korean parade. Foreign Ministry spokesman Liu Weimin told a regular news conference that China is against the spread of weapons of mass destruction and carriers for such weapons.

State Department spokeswoman Victoria Nuland said in a briefing Friday that the United States has raised the issue of alleged missile assistance to North Korea with China as part of their ongoing discussions. China has said in the past that it is complying fully with U.N. Security Council resolutions sanctioning North Korea, State Department spokesman Mark Toner said a day earlier.

The carrier, also believed capable of launching missiles, was the biggest yet displayed by North Korea and gives the country the ability to transport long-range missiles around its territory, making them harder to locate and destroy.

Analyst Ted Parsons of IHS Jane's Defence Weekly first raised the possibility that the missile-carrying vehicle came from China, citing similarities to Chinese design patterns.

North Korean space officials, meanwhile, said in a statement Thursday that they will keep pushing forward with their space development program. Washington says the North's rocket launch was a cover for a missile test.