Iran has continued to use front companies to illicitly purchase banned items for nuclear and missile production even after coming to an interim agreement with Western nations over its controversial nuclear program, a U.S. official told Reuters.

Vann Van Diepen, the U.S. State Department’s principal deputy for nonproliferation issues, told Reuters on Sunday that Iran was still “very actively” creating front companies as well as trying to hide its purchases in other ways.

“They still continue very actively trying to procure items for their nuclear program and missile program and other programs,” Van Diepen said.

In this Oct. 26, 2010 file photo, a worker rides a bicycle in front of the reactor building of the Bushehr nuclear power plant, just outside the southern city of Bushehr. (AP Photo/Mehr News Agency, Majid Asgaripour, File)

In this Oct. 26, 2010 file photo, a worker rides a bicycle in front of the reactor building of the Bushehr nuclear power plant, just outside the southern city of Bushehr. (AP/Mehr News Agency, Majid Asgaripour, File)

“We continue to see them very actively setting up and operating through front companies, falsifying documentation, engaging in multiple levels of trans-shipment … to put more apparent distance between where the item originally came from and where it is ultimately going,” he added.

The Times of Israel newspaper observed: “The illicit activity would lend some credibility to those who argue that the sanctions relief has opened the door for Iran to do more illicit business.”

A senior Iranian official told Reuters he had “no comment” about the allegation. Iran’s longstanding position is that its nuclear program is solely for peaceful purposes.

Reuters noted that the supplies being pursued are not in violation of the historic agreement reached in November between Iran and six world powers, including the U.S., in which international sanctions would be eased in exchange for Iran limiting its nuclear aspirations.

However, the purchases “would breach a 2006 U.N. embargo banning the provision by any nation to Iran of materials related to its nuclear and missile development work,” Reuters noted.

When asked if he had seen a change in Iran’s procurement posture in the past six months to one year, Van Diepen replied, “The short answer is no.”

The State Department official did not specify which components Iran has tried to purchase.

Van Diepen said that while there is no direct link between Iran’s secret procurement and the negotiations, “obviously if the negotiations succeed then there should therefore be a corresponding decrease in Iranian proliferation activity.”

Israeli Prime Minister Benjamin Netanyahu last week slammed Western nations for believing that Iran has abandoned its nuclear weapons ambitions.

The Israel Defense Forces earlier this month intercepted a shipment of what it said were Iranian weapons headed to terrorist groups in Gaza, including 40 long-range rockets, 181 mortars and 400,000 bullets.

Speaking at an event at which the seized weapons were displayed for the media last week, Netanyahu the nations engaged in talks with Iran “want to delude themselves that Iran abandoned its goal of obtaining nuclear weapons.”

The latest round of talks over Iran’s nuclear program were held in Vienna last month. A new round is scheduled for Tuesday and Wednesday.

Iranian Foreign Minister Mohammad Javad Zarif said on Sunday that the Islamic Republic does not expect to cement a final deal with negotiators this week.

“We don’t expect to reach a deal in this round of talks … We have agreed to discuss a number of issues in this round,” Zarif told reporters in Tehran.