(Reuters) - Lawyers for the United States on Monday urged jurors to allow the U.S. government to seize a Manhattan office tower from a non-profit for violating U.S. sanctions against Iran.

In closing arguments at the end of a month-long trial in Manhattan federal court, Assistant U.S. Attorney Michael Lockard told jurors that the non-profit Alavi Foundation, the building’s majority owner, knew its minority partner, Assa Corp, was a front for Iran’s government and helped hide that fact.

“They knew that when that secret got out, they stood to lose everything,” he said.

The government wants to seize the 36-story building at 650 Fifth Avenue, likely worth close to $1 billion, to benefit people with judgments against Iran relating to bombings and other attacks.

John Gleeson, arguing for Alavi, did not dispute that Alavi knew Assa was owned by Iran’s state-controlled Bank Melli when it entered into a partnership with it in 1989.

But he said the foundation, established in the 1970s by the Shah of Iran to promote Persian and Islamic culture in the United States, was led to believe that Assa was sold before 1995, and was misled when it tried to learn more.

“At every turn, it was either ignored, or given the run-around, or lied to,” Gleeson said.

Lockard told jurors that Alavi continued to turn rental income from the building over to Assa after the United States imposed sanctions on Iran in 1995, violating those sanctions.

He pointed to evidence including testimony from former Alavi board member Seyed Mojtaba Hesami-Kiche, a key government witness. He said a letter from another former board member to Iran’s Supreme Leader Ali Khamenei referred to the United States as “the Great Satan” and suggested Alavi was working for Iran.

Lockard acknowledged that much of the evidence was from before 1995, but said Alavi personnel did not “forget” who controlled Assa when the sanctions took effect.

Gleeson described Alavi as a legitimate non-profit raising money for charitable activities.

He attacked the credibility of Hesami-Kiche, who was paid by the U.S. government and admitted on the stand that he initially failed to pay taxes on that money.

Gleeson is expected to continue his arguments on Tuesday. The government will be allowed a brief response.