A US scientist and his wife who worked at the leading nuclear research site were arrested Friday and charged with trying to sell secrets to help Venezuela start a nuclear weapons program, US officials said.

The pair, both US citizens, "have been indicted on charges of communicating classified nuclear weapons data to a person they believed to be a Venezuelan government official and conspiring to participate in the development of an atomic weapon for Venezuela," the US Justice Department said in a statement.

The defendants, Pedro Mascheroni, 75, and Marjorie Roxby Mascheroni, 67, had both worked as contractors at the Los Alamos National Laboratory in the southwestern state of New Mexico, and could face life in prison if convicted on all charges.

They had sought 793,000 dollars in payment for the restricted and classified data which they believed they had provided to a Venezuelan contact, but who was actually an undercover FBI agent.

The Justice Department was quick to acknowledge that the indictment does not allege any wrongdoing by the Venezuelan government or anyone acting on its behalf, and also said no one currently working at Los Alamos was charged or accused of wrongdoing.

But the revelations could still sharpen relations between the United States and Venezuela, whose firebrand leftist President Hugo Chavez is a vocal critic of Washington.

FBI agents arrested Mascheroni -- a naturalized US citizen from Argentina -- and his US-born wife early Friday.

According to the statement, among the 22 indictments, the defendants are charged with "communicating 'restricted data' to an individual with the intent to injure the United States and secure an advantage to a foreign nation," conspiring to participate in development of an atomic weapon, concealing US records, and several counts of making false statements.

The department revealed a series of startling details about the couple's plans to pass the nuclear secrets to Venezuela, beginning in March 2008 when the husband had conversations with the undercover agent.

During the talks, Pedro Mascheroni "allegedly said he could help Venezuela develop a nuclear bomb within 10 years and that, under his program, Venezuela would use a secret, underground nuclear reactor to produce and enrich plutonium, and an open, above-ground reactor to produce nuclear energy," according to the Justice Department.

Pedro Mascheroni is a physicist who worked at Los Alamos from 1979 to 1988, while his wife worked there between 1981 and this year, the Justice Department said. Both held security clearances that allowed them access to certain classified information.

"The conduct alleged in this indictment is serious and should serve as a warning to anyone who would consider compromising our nation's nuclear secrets for profit," Assistant Attorney General David Kris said.

In talks with the undercover agent, Mascheroni allegedly asked about obtaining Venezuelan citizenship, and described how he expected to be paid.

In July 2008, the undercover agent gave Mascheroni 12 questions purportedly from Venezuelan military officers and scientists, and months later Mascheroni delivered at the post office box being used as a dead drop location a disk with a 132-page document on it laying out his plan for a nuclear weapons development program.

Nearly one year later Mascheroni received another list of questions from the "Venezuelan officials" and 20,000 dollars in cash as a first payment. "On his way to pick up these materials, he allegedly told his wife he was doing this work for the money and was not an American anymore," the indictment said.

One month later Mascheroni took a disk to the dead drop location that contained a 39-page document answering the questions -- and allegedly included "Restricted Data" related to nuclear weapons.

The couple later lied about their involvement when FBI agents questioned them about the classified information delivered to the undercover agent.

The indictment "contains allegations only and that every defendant is presumed innocent unless and until proven guilty," the statement said.