Leader of the Islamic Revolution Ayatollah Imam Sayyed Ali Khamenei warned that the harsh tone by the West, especially the US, concerning the nuclear talks with Iran is part of their tricks and ploys.

Leader of the Islamic Revolution Ayatollah Imam Sayyed Ali Khamenei warned that the harsh tone by the West, especially the US, concerning the nuclear talks with Iran is part of their tricks and ploys.

In a meeting with the members of the Assembly of Experts and the body's newly-elected Chairman Ayatollah Mohammad Yazdi on Thursday, Imam Khameni urged the Iranian negotiators in the nuclear talks with the P5+1 group of world powers to exercise vigilance over the subterfuge of the other side.   

"Of course I am worried, because the other side is known for opacity, deceit and backstabbing,” Mehr news agency quoted the Leader as saying during the meeting which was also attended by President Hassan Rouhani.

"Every time we reach a stage where the end of the negotiations is in sight, the tone of the other side, specifically the Americans, becomes harsher, coarser and tougher. This is the nature of their tricks and deceptions,” his eminence added.

Meanwhile, he slammed a letter sent by US senators to Iranian officials, saying it revealed the collapse of political ethics in the US system.

The letter signed by 47 Republican senators warned Iran that any nuclear deal made with U.S. President Barack Obama, a Democrat, could last only as long as he remained in office - an unusual intervention into US foreign policy-making.

The White House has described the letter as "reckless" and "irresponsible," saying it interfered with efforts by six major powers to negotiate with Iran over its nuclear program.