"Crushed and outraged" relatives of an American missing in Iran for nine years expressed deep frustration that he was not included in a prisoner exchange over the weekend.

"Why did Iran prisoner swap not include my father?" asked Sarah Moriarty, daughter of ex-FBI agent Robert Levinson, who has been missing for nearly a decade.

Levinson, 67, disappeared in mysterious circumstances in March 2007 during a visit to the Iranian island of Kish.

He was reportedly investigating cigarette counterfeiting in the region.

Speaking on behalf of her "crushed and outraged" family, Moriarty noted the capture and US negotiations for the release of a number of Americans during her father's long captivity -- 3,237 days thus far.

"We are happy for their families. We shared their pain. But this news deeply hurts. And we can't hold back our devastation, let alone our anger, any longer," she wrote on CNN.com.

Of the US citizens who have been freed by Iran, four were part of a prisoner swap with America, while a fifth was released in a separate process.

In exchange, Washington granted clemency to seven Iranians. And it withdrew international arrest notices for 14 Iranians.

- 'Betrayal' -

Moriarty denounced "the calculated risk that was taken to decide that five hostages were enough for this deal."

"A deadline to wrap up everything about our current relations with Iran in a pretty bow on January 16... meant to our family that our government was satisfied with leaving my father behind. Again," Moriarty added.

"We watch as the TV cameras and newspaper and Internet headlines capture every moment of these families happily embracing their long-missed loved ones, while my father, the longest-held hostage in American history, languishes somewhere over there, growing weaker by the day. All but forgotten. Again."

She also spoke of the American government's "betrayal" for not giving Levinson's family advance warning of the prisoner exchange.

Moriarty noted that US officials took more than an hour to confirm to his wife that he was not part of the deal.

"We are thankful that the president mentioned my father in his speech on Sunday, but he has yet to reach out to my mom to tell her what 'cooperating' means, or what he is doing next to get my dad home," Moriarty wrote.

"We believe the US government did not use the best leverage it ever had to demand that my dad be brought home."

Although there has been no official confirmation of Levinson's whereabouts for the better part of a decade, Moriarty insisted: "my family believes Iran knows exactly where my father is and that our government is aware of this."

She vowed never to give up until Levinson is reunited with his family.

"We will not go away. We will not be silent. We will never give up, we will never stop -- until my father is home," Moriarty wrote.

Source: AFP