Washington is responsible for stopping negotiations in Vienna, Iranian Foreign Ministry spokesman Saeed Khatibzadeh said, Mehr reported.

He said if the White House responds logically to Iran's reasonable demands, which are approved by the P4+1 group, Tehran will be ready to return to Vienna.

He noted that Washington is trying to link the remaining issues to its domestic problems. The Iranian side cannot wait forever, a senior Iranian diplomat said, adding that if the United States wants to reach an agreement, it must make a political decision as soon as possible.

The negotiation process on the remaining issues has been suspended for several weeks, he said, pending a political decision by Washington.