In a letter to UN Secretary-General Antonio Guterres, Majid Takht-Ravanchi said Tehran “expects the UN to shoulder its responsibilities” to prevent the US from providing support to terrorist groups.

Takht-Ravanchi added that as admitted by the group, it has carried out several terrorist attacks in the country that killed or injured a number of civilians.

However, the group is still conducting its acts of terror from inside the United States and is even training terrorists to carry out acts of sabotage in Iran, he added.

Takht-Ravanchi emphasized that Iran has on numerous occasions informed the United States of the group’s terrorist crimes through the Swiss Embassy in Tehran, which represents the American interests section, but Washington has so far carried out no measure to prevent acts of terror by the group’s members or extradite them to Iran for trial.

He said that US was in “full knowledge of all terrorist and criminal activities of the group and its members”.

“Despite being cognizant of the group’s terrorist nature and activities, the United States, to date, has continued to sponsor it and has refrained from taking even the slightest measure to prevent the terrorist activities of this group,” Takht-Ravanchi said.

The US is responsible for all the group’s crimes committed in Iran and “the loss of lives of the Iranian citizens and the damages inflicted as a result of such acts”, he said.

Based on international law, countries are committed not to support terrorists and allow them to use their soil for terrorist acts against other states, the envoy said.

He added that the continuation of the US support for the Tondar group leaves no doubt that Washington is blatantly violating all its international obligations and therefore is liable for all criminal acts committed by the group’s members in Iran.

The Iranian Intelligence Ministry said on August 1 that it had arrested Jamshid Sharmahd, the ringleader of the Tondar terrorist group.

In a statement, the ministry said Iranian security forces had managed to arrest Sharmahd, who directed “armed operations and acts of sabotage” in Iran from the US.

Following a complicated operation, the ringleader of the group, was arrested and he is “now in the powerful hands” of Iranian security forces, it added.

Upon his arrest, Sharmahd admitted providing explosives for a 2008 attack against a religious congregation center in the southern Iranian city of Shiraz, Fars Province, in 2008 that killed 14 people and wounded 215 others.

“I was called before the bomb was about to be set off. They were in a good position. They [just] needed explosives that we provided for them,” Sharmahd said.

Tondar had plotted several big operations” including attempting to blow up the Sivand dam in Shiraz, detonating “cyanide bombs” at a Tehran book fair, and planting an explosive device at the mausoleum of the founder of Islamic Republic Ayatollah Rouhollah Khomeini.

Press TV contributed to this story.