The United States on Thursday displayed pieces of what it said were Iranian weapons deployed to militants in Afghanistan and Yemen.

The second presentation of Iranian weapons by the Pentagon, many of which were handed over by Saudi Arabia, coincides with growing concern in Congress over US military support for the Saudi-led coalition in Yemen's civil war, which has led to a deep humanitarian crisis, Reuters said in a report.

Brian Hook, the US Special Representative for Iran, told reporters the Iranian threat is growing and warned of an "accumulating risk of escalation" in the region if the United States fails to act.

"Today we are unveiling Iran's Sayyad-2 C surface to air missile which you see behind me. This missile was designed and manufactured in Iran and the writing in Farsi on its side translates as 'the hunter missile.' The conspicuous Farsi markings is Iran's way of saying they don't mind being caught violating UN resolutions," Hook said.

"Fajr rockets have also been added to the display and are located next the anti-tank guided missiles. These weapons were recovered in Helmand, near Kandahar Air Field, by the Afghan National Army from the Taliban. Iran has been providing materiel support to the Taliban since at least 2007. These same rockets have been used by Hamas in the past," he added.

Giving more details on the weaponry, he said: "To my left is a new unmanned aerial system: the Shahed 123. We have debris from a Shahed which was recovered by coalition forces in Afghanistan after it crashed, as well as Shahed components that were interdicted in Yemen in early 2018."

The presentation, the second such one in the last year, is part of a government-wide effort to follow through on Trump's policy to take a far harder line toward Tehran.

The US president pulled the United States out of the Iran nuclear deal and reimposed sanctions, in part for its "malign" regional activities.

Iran has often denied any aid to the Taliban in Afghanistan. Meanwhile, Iran has denied supplying the Houthis in Yemen with such weaponry and described the Pentagon's previous arms display as "fabricated."

Iran’s Embassy in Kabul in a statement meanwhile rejected the remarks by Brian Hook and called them “baseless”.

The statement said that these remarks are aimed at justifying some “hurriedly and non-transparent” attempts by US in Afghanistan and damaging the growing relations of Iran and Afghanistan.

Taliban in a statement has labeled the US findings as "baseless"