The United States paid $1.7bn to Iran as settlement for failed arms deal

Fifth Amendment keeps people from being witnesses against themselves

Said Attorney General had refused to answer 'straightforward' questions

Loretta Lynch is 'pleading the fifth' to dodge questions about $1.7 billion payments made by the United States to Iran, two members of Congress have claimed.

Senator Marco Rubio and Representative Mike Pompeo wrote a letter to Attorney General Lynch Friday, accusing her of refusing to answer 'straightforward questions' about the payments.

The Fifth Amendment keeps people from having to be witnesses against themselves in a criminal case. Commonly, 'pleading the fifth' means refusing to provide information that might incriminate oneself.

The United States gave $.17 billion to Iran in three different payments, the first of which, worth $400,000 was made in January.

Loretta Lynch (pictured on Tuesday) is 'pleading the fifth' to avoid answering questions about $1.7 billion payments to Iran, Senator Marco Rubio and Representative Mike Pompeo claimed

Tehran agreed to release four American prisoners the same day, prompting Republicans to denounce the payment as ransom. Rubio has been one of the most vocal voices supporting that claim, which the White House has denied.

Rubio and Pompeo's letter, published by the Washington Free Beacon, a Conservative website, begins by slamming Lynch for failing to answer 'any' of their questions.

'As the United States' chief law enforcement officer, it is outrageous that you would essentially plead the fifth and refuse to respond to inquiries,' Rubio and Pompeo wrote.

'The actions of your department come at time when Iran continues to hold Americans hostage and unjustly sentence them to prison.'

Rubio (left) and Pompeo (right) wrote a letter to Attorney General Lynch Friday, accusing her of refusing to answer 'straightforward questions' about the payments

The United States' payment to Iran settled a decades-long failed arm deal dating back to before 1979.

Iran had ordered and paid $400,000 worth of fighter jets, but the United States froze the delivery when the Shah was overthrown in 1979.

The United States paid back these $400,000 plus $1.3 billion of interest.

Barack Obama announced the payments in January, when the Iran deal was struck.

'The United States and Iran are now settling a longstanding Iranian government claim against the United States government. Iran will be returned its own funds, including appropriate interest, but much less than the amount Iran sought,' he said.

Rubio in September became the main sponsor of a bill that would bar similar payments to Tehran until Iran pays the nearly $55.6 billion that US courts say Iran owes to American victims of Iranian terrorism.