"Efforts from Iran and the port organization have been made for the release of this ship", he was quoted as saying.
Speaking at a press conference on Tuesday, the deputy director of the Ports and Maritime Organization of Iran for maritime affairs, Jaleel Eslami, said the United Kingdom is going to let Iran's supertanker go.
The deputy head of Iran's Ports and Maritime Organisation, Jalil Eslami, said in remarks reported by state news agency IRNA that Britain was thinking of freeing the Grace 1 following an exchange of documents.
Eslami also defended Tehran's confiscation on July 19 of the 30,000-tonne UK-flagged Stena Impero tanker, which was violating global maritime rules while passing through the Strait of Hormuz. A court in Gibraltar will decide the fate of the ship on Thursday, when an order for its detention lapses.
The official said a report by Iran's semi-official Fars news agency that the Grace 1 tanker is leaving Tuesday night are "untrue".
Tensions in the Persian Gulf have been rising since the United States pulled out of the global 2015 nuclear treaty, under which Iran agreed to curb its nuclear work in return for lifting most worldwide sanctions on Tehran.
Last month British marines seized an Iranian tanker, named Grace 1, off the coast of Gibraltar on suspicion it was taking 2.1 million barrels of oil to Syria - in breach of an European Union arms embargo.
Although Grace 1 was seized by British forces, Britain said on Tuesday that investigations into the tanker Grace were a matter for Gibraltar.
Washington has developed a plan to create a military coalition to escort foreign vessels sailing through the Strait of Hormuz in the strategic Persian Gulf. Tehran denies that the tanker was heading to Syria and calls Britain's actions "maritime piracy".
Last week, Israel's Ynet website reported that Israel is providing intelligence and other, unspecified assistance to US -led efforts to protect Persian Gulf shipping routes.