TEHRAN (FNA)- Commander of Iran's Basij (volunteer) Force Brigadier General Mohammad Reza Naqdi said the US agreed to release $1.7 of Iran's frozen funds in a bid to buy freedom of its spies held by Tehran.

The US agreed to repay Iran a $400 million debt and $1.3 billion in interest dating to the Islamic revolution.

"The annulment of sanctions against Iran's Bank Sepah and reclaiming of $1.7mln of Iran's frozen assets after 36 years showed that the US doesn’t understand anything but the language of force," Naqdi said, addressing Basij forces in Tehran on Wednesday.

"This money was returned for the freedom of the US spy and it was not related to the (nuclear) negotiations," he added.

4 Iranian-American nationals who were held for various charges in Iran were freed under a prisoners swap deal on Saturday after the implementation of the nuclear deal clinched between Tehran and the world powers in July. A fifth inmate was also released separately.

"Based on an approval of the Supreme National Security Council (SNSC) and the overall interests of the Islamic Republic, four Iranian prisoners with dual-nationality were freed today within the framework of a prisoner swap deal," the office of Tehran prosecutor said.

The four Iranian-Americans, Jason Rezaian, Amir Hekmat, Saeed Abedini and Nosratollah Khosrawi Roudsari who were jailed in Iran on various charges in recent years, have all been released.

Meantime, a US official said a fifth dual nationality prisoner would also be released by Iran separate from the swap deal. Later reports named this fifth prisoner as Mathew Trevithick.

According to the swap deal, the US also freed 7 Iranian-Americans who were held for sanctions-related charges and asked the Interpol to stop prosecution of 14 other Iranian nationals. But according to what Iran's Foreign Ministry Spokesman Hossein Jaberi Ansari said on Monday, the number of the Iranians whose charges have been dropped stands at 21.

The 7 Iranian inmates freed by the US were named as Nader Modanlou, Bahram Mechanic, Khosrow Afqahi, Arash Ghahreman, Touraj Faridi, Nima Golestaneh and Ali Sabounchi.

The 14 Iranians who were mentioned in earlier reports and had charges dropped on Saturday included Saeed Jamili, Jalal Salami, Matin Sadeqi, Alireza Moazzemi Goudarzi, Mohammad Abbas Mohammadi, Kourosh Taherkhani, Sajjad Farhadi, Seyed Ahmad Abtahi, Gholamreza Mahmoudi, Hamid Arabnejad, Ali Moattar, Mohammad Ali She'rbaf, Amin Ravan and Behrouz Dolatzadeh.

Jaberi Ansari did not name the other 7 Iranians whose charges have been dropped.

Some reports earlier this year had spoken of a potential prisoner swap between Iran and US following the Vienna nuclear deal in July.

By Fars News Agency