President Moon Jae-in's senior politics secretary on Tuesday dismissed a nagging controversy over his chief of staff's recent visit to the United Arab Emirates, saying it was aimed at delivering handwritten letter from Moon aimed at enhancing bilateral ties.

Han Byung-do also called speculation over Chief of Staff Im Jong-seok's trip to the Middle East earlier this month "groundless" and noted that the presidential office could not elaborate much on Im's talks with UAE leaders due to diplomatic protocol.

Rumors have swirled that Im hurriedly traveled to the UAE to allay its concerns about the possible impact of Moon's nuclear phase-out policy on a set of bilateral deals in which Seoul is to export and operate four nuclear reactors in the Middle East country.

"In June, President Moon had phone talks with the UAE crown prince, and the content regarded further improving bilateral friendly and cooperative relations," Han told reporters.

"Im was supposed to visit the Dongmyeong unit (in the UAE) to encourage South Korean troops; we informed (the UAE) of his visit and we then asked them what they thought about him delivering (Moon's) handwritten letter -- and they said they would welcome it," he added.