Israel has been operating special forces teams on the ground in Iran in an attempt to collect evidence on the Islamic Republic's contentious nuclear program, the Sunday Times reported on Sunday, citing western intelligences sources.

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The report came after a New York Times report earlier this month, which claimed that Israel’s intelligence services agree with American intelligence assessments that there wasn't not enough proof to determine whether Iran is building a nuclear bomb.

The newspaper said that senior American officials believe there is little disagreement between the Mossad and U.S. intelligence agencies over Iran’s nuclear program, despite the fact that Israeli political leaders have been pushing for quick action to block Iran from becoming what they describe as an existential threat.

The report further quoted one former senior American intelligence official who states that the Mossad “does not disagree with the U.S. on the weapons program,” adding that there is “not a lot of dispute between the U.S. and Israeli intelligence communities on the facts.”

On Sunday, however, western intelligence sources indicated to the Sunday Times that Israel was actively searching for "smoking gun" evidence that would point at the Iranian program's military dimensions.

According to the report, Israel was using a permanent base in northern Iraq, from which special forces teams, disguised as members of the Iranian military, enter Iran on board Black Hawk helicopters.

The report added that the Israeli teams use sensitive equipment to monitor the radioactivity and magnitude of explosives tests suspected to have been carried out near at the Parchin military base near Tehran.

"We've detected clean-up efforts recently in Parchin, which might indicate that the Iranians are trying to hide evidence of warhead tests in preparation for a possible IAEA visit," an unnamed sources told the Sunday Times.

Also on Sunday, U.S. President Barack Obama said there was still time to resolve the Iranian nuclear standoff through diplomacy, but that the window for such a solution was closing.

Obama reiterated his position on the Iran nuclear issue after talks with Turkish Prime Minister Tayyip Erdogan on the eve of a nuclear security summit in Seoul.

"I believe there is a window of time to solve this diplomatically, but that window is closing," Obama told reporters.

Obama has pressed Israel to hold off on any attack on Iran's nuclear sites to give sanctions and diplomacy time to work, but has said military action remains an option if all else fails