DUBAI, May 19. /TASS/. Iran has not yet received any official proposals mentioned by US President Donald Trump on settling the crisis around its nuclear program, Iranian Foreign Ministry Spokesman Esmail Baghaei said.

"We have not yet received any written offers from the US side. All the proposals were verbal: during talks via Omani mediators or during breaks between the negotiations. But we were not given any formal documents," the diplomat said at a weekly briefing.

"Additionally, these verbal proposals are constantly changing. Negotiators or other authorized US officials keep raising new issues which seriously disrupts the negotiation process. It is quite difficult to hold it when one of the sides is totally inconsistent in relaying its stance and constantly changing the language used," Baghaei added.

On May 11, Iran and the US held a fourth round of talks on Tehran’s nuclear program. At the consultations, the Iranian delegation was led by Iranian Foreign Minister Abbas Araghchi, while US Special Presidential Envoy Steve Witkoff led the American delegation.

Following the talks, the top Iranian diplomat noted that this round was more serious and sincere than the previous ones while the positions of the two sides had become somewhat closer.

On May 16, Trump said that Washington sent to Tehran a written proposal on settling the situation. Witkoff noted that the US side’s principled stance is Iran’s complete abandonment of enriching uranium, that is, the dismantling of its nuclear program.

The Iranian Foreign Ministry earlier said that in the event the sanctions are lifted, Tehran is ready to discuss with the US the restriction of volumes and levels of enriching uranium but will never completely shut down its nuclear program as the right to peaceful nuclear development is guaranteed to all the countries that signed the Treaty on the Non-Proliferation of Nuclear Weapons (NPT), where Tehran was one of the first signatories.

Earlier, Iran vowed to withdraw from the NPT if the snapback mechanism, allowing for the return of all UN Security Council sanctions against Tehran that were suspended under the 2015 Joint Comprehensive Plan of Action (JCPOA), is activated.