Iran has created a plan B for nuclear  weapons capacity in a second plant, satellite images indicate, as world powers awaited Tehran's response to nuclear talks.
The IR-40 40-megawatt thermal nuclear reactor in Arak -- said by the regime of President Mahmoud Ahmadinejad to produce power and isotopes -- has begun heavy-water production, satellite images commissioned by The Daily Telegraph in London indicated.
The images, taken Feb. 9, show signs of activity at the Arak plant, 150 miles southwest of Tehran, including a cloud of steam analysts said indicates heavy-water production.
The images also show numerous surface-to-air missile and artillery sites to protect the plant. The protection is far more extensive than at any other known Iranian nuclear  site, the Telegraph said.
The missile defenses are most heavily concentrated west of the plant, which the newspaper said would be the most direct line of approach for any aircraft delivering a long-range strike from Israel.
Arak  is surrounded by mountains on the west, south and east.
Israel has warned it may carry out military strikes to stop Iran from gaining nuclear-weapons  capacity. Washington says it won't rule out using force but prefers diplomacy.
Western governments and the U.N. nuclear watchdog the International Atomic Energy Agency have privately had information about the Arak activity for some time, the Telegraph said.
The Obama administration had no immediate comment on the report.
The steam indicates that the heavy-water plant is operational and the extent of the air-defense emplacements around the site make it suspicious, Stuart Ray, operations manager at Britain's McKenzie Intelligence Services Ltd. consulting firm, told the Telegraph.
Heavy water, formally called deuterium oxide, or 2H2O, contains heavy hydrogen, or deuterium, rather than the common hydrogen in normal water.
Heavy water is needed to operate a nuclear reactor that can produce plutonium, which could then be used to make a bomb.
The Telegraph published the images as talks between Iran and six world powers over its nuclear program went into a second day, with Western diplomats waiting for a response from Tehran to an offer of sanctions relief in return for Iranian confidence-building measures.
The talks, in Almaty, Kazakhstan, included an offer addressing concerns on the exclusive peaceful nature of the Iranian nuclear program  but was also responsive to Iranian ideas, said Michael Mann, spokesman for EU foreign-policy chief Catherine Ashton, who leads the team representing the United States, Britain, France, China, Russia and Germany.
Those countries are the five permanent members of the U.N. Security Council, plus Germany, known as the P5-plus-1.
Mann didn't give details, but several news organizations said the team offered Tuesday to ease sanctions  so Iran can resume its gold and precious metals trade as well as some international banking and petroleum trade, if Iran shuts down its deep-underground Fordo uranium-enrichment plant south of Tehran, near the holy city of Qom.
Iran has consistently refused to do this.
During the 2 1/2-hour session the P5-plus-1 delegates also said they wanted Iran to stop enriching uranium  to 20 percent and to get rid of the uranium it has already enriched to 20 percent purity, the news organizations said.
Twenty-percent enrichment puts Iran a few technical steps away from weapons-grade uranium.
Iran has been stockpiling enriched uranium for years in defiance of Security Council resolutions demanding it halt the activity until it can satisfy the IAEA  it has no weapons program and no hidden enrichment sites.
In return for complying with the Security Council demands, all sanctions -- which have cut 8 percent out of Iran's gross domestic product, rocketed inflation and collapsed its currency's value -- would be lifted, the P5-plus-1 countries said.
Russian delegate Deputy Foreign Minister Sergei Ryabkov, a staunch opponent of increasing sanctions, told the Russian non-governmental news agency Interfax time was running out for the talks.
Iranian state television described the talks' atmosphere as very serious.
Iranian negotiators planned to respond with proposals based on ideas Tehran put forward at the last talks in Moscow eight months ago, an Iranian official said.