Iran has successfully produced and tested fuel rods for use in its nuclear power plants, state television reported on Sunday, in a snub to international demands that it halt sensitive nuclear work. The rods, which contain natural uranium, were made in Iran and have been inserted into the core of Tehran's research nuclear reactor, the television reported. Nuclear fuel rods contain small pellets of fuel, usually low-enriched uranium, patterned to give out heat produced by nuclear reaction without melting down. "This great achievement will perplex the West, because the Western countries had counted on a possible failure of Iran to produce nuclear fuel plates," the Tehran Times newspaper said. The development was announced at a time of growing tension between Western powers and Iran after the U.N. nuclear agency reported in November that Tehran appeared to have worked on designing a nuclear weapon. Secret research to that end may be continuing, it said.