"We are soon going to send a letter indicating our intention and our readiness to accede to the protocol," said Iran's representative to the IAEA, Ali Akbar Salehi.
"A letter has been drafted. It has been given to officials. They are studying it," he added, explaining that the final say now rested with Hassan Rowhani, the secretary of Iran's Supreme Council of National Security.
Iran pledged to sign the protocol during a visit to Tehran on October 21 by the foreign ministers of Britain, France and Germany, which extracted a series of concessions from the Islamic republic over its nuclear programme.
Salehi said he expected a decision to be made and the IAEA to be informed in the coming days -- well ahead of the IAEA's next board of governors' meeting on November 20.
"It's a matter of days," he said, adding that Iran has attached "no conditions" to signing the protocol.
"It will be distributed and tabled to the board. The board has to endorse it and authorise the (IAEA) director general (Mohamed ElBaradei) to go into the process of signature with the Islamic Republic of Iran," he explained.