Washington is directly responsible for the delay in reaching a nuclear deal, Iran’s foreign minister told his Omani counterpart in a conversation late on Sunday.

Sayyid Badr Albusaidi, Oman’s foreign minister and Hossein Amir-Abdollahian discussed regional developments in a phone call, including a ceasefire that went into effect in Yemen on Saturday and nuclear talks between Iran and the United States, the government news website IRNA reported.

Officials of Muslim countries have been making calls on Sunday, on the occasion of Ramadan that started on Saturday in many Sunni countries and on Sunday in Iran.

Amir-Abdollahian criticized recent sanctions imposed by the US on some Iranian persons and companies, saying that Tehran is ready for a “good and lasting” agreement but the “American side has some maximalist demands and is directly responsible for the prolongation of the [nuclear] talks.”

Washington sanctioned an Iran-based network on March 30 for its role in procurements boosting Iran’s ballistic missile program, seen by many regional countries and the United States as a threat.

Although nearly one year of negotiations in Vienna were said to have reached its final stage, Tehran has demanded that the US remove its Revolutionary Guard from its list of ‘foreign terrorist organizations’. The Biden administration has apparently not made a decision yet, amid rising opposition by Republicans and some Democrats in Congress.