A report looking at Iran's nuclear plans is expected to reveal that the country has been receiving help from Russia, Pakistan and North Korea.
The International Atomic Energy Agency quarterly report into Tehran's nuclear ambitions is due to be released this week and it is understood to include claims that Russian scientists advised the regime on "how to build high-precision detonators that can be used to trigger nuclear chain reactions."
The UN nuclear watchdog is in charge of monitoring compliance with the Nuclear Non-Proliferation Treaty.
According to the Telegraph, one of its key findings is that Iran is "in the advanced stages of designing a nuclear explosive device small enough to fit in a warhead".
The report is also understood to say that for five a years a former Soviet scientist aided Iran without permission from Moscow, and to confirm that Iran is producing enriched uranium near Qom.
The report comes amidst speculation that Israel or the United States is considering military action to strike Iran's nuclear facilities preemptively.
Iran's President Mahmoud Ahmadinejad, said Washington would "not be able to" save Israel. He said: "This entity [Israel] can be compared to a kidney transplanted in a body that rejected it. It will collapse and its end will be near," he said.