Iran on Tuesday denied foreign media reports that it is preparing to test the final component of a nuclear bomb, IRNA news agency reported.

The Times referred to secret documents on Monday suggesting that Iran is working on testing a trigger mechanism for a nuclear bomb. On Tuesday, the paper quoted a senior U.S. official as saying the intelligence "certainly gives urgency...in terms of additional pressure on sanctions" against Tehran.

Foreign Ministry spokesman Ramin Mihman-Parast said the reports were groundless, dismissing them as "propaganda warfare" and "politically motivated media schemes," IRNA reported.

The remarks came after China on Tuesday withdrew from a crucial meeting of the six powers involved in the long-running nuclear dispute with Tehran, which is due on December 22.

The United States has stepped up efforts to persuade China and Russia to back a new set of tougher sanctions against Iran since the exposure of a secret nuclear facility in the country and over its reluctance to accept an IAEA-backed uranium enrichment deal.

Asked about possible new sanctions at a news briefing, Mihman-Parast said they are not effective against Iran and would be "no use at all." He said sanctions have only "served to strengthen Iran's will to continue with its program," IRNA reported.

Tehran has insisted it needs nuclear technology to generate electricity, dismissing Western suspicions of its covert weapons program.

MOSCOW, December 15 (RIA Novosti)