(Reuters) -- 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, containing natural uranium, were made in Iran and have been inserted into the core of Tehran's research nuclear reactor, state 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.
The United States and its European allies have increased the sanctions pressure on Iran, one of the world's largest oil producers, to push Tehran to halt the enrichment.
U.S. President Barack Obama signed more sanctions against Iran into law on Saturday, shortly after Iran signaled it was ready for new talks with the West on its nuclear program and said it had delayed long-range missile tests in the Persian Gulf.
Western analysts say Iran sometimes exaggerates its nuclear advances to gain leverage in its stand-off with the West.
In April, Iran's Atomic Energy Organization announced that the installation of the machinery needed for producing nuclear fuel plates had started. The nuclear plant for converting enriched nuclear fuel into fuel rods was inaugurated in 2009.
Currently, the rod is also undergoing rays at Tehran's Research Reactor to examine its long-term performance, Iran's English-language Press TV reported.
Iran says only a few countries are capable of making both the fuel plates, used in the Tehran reactor, and nuclear fuel rods, which are used in power stations.
Enriched uranium can be used to fuel power plants and other types of reactors, which is Iran's stated aim, or to provide material for atomic bombs if processed much further, which the West suspects is the country's ultimate intention.
Tehran says it needs nuclear technology to generate electricity.
Iran's decision last year to raise the level of some enrichment from the 3.5 percent purity needed for civilian power plant fuel to 20 percent worried Western states that feel this will bring Tehran much closer to the 90 percent suitable for an atomic bomb.
Tehran has so far refused to change its nuclear course, but is ready to hold new talks to resolve the dispute. Negotiations between Iran and the five permanent members of the U.N. Security Council -- the United States, Russia, China, Britain and France -- plus Germany (P5+1) stalled in January.
(Writing by Parisa Hafezi; Editing by Angus MacSwan)