A spokesperson for the U.K. Foreign Office said that the "ongoing investigation" into the Grace 1 was a matter for Gibraltar authorities.
The official said London had shown willingness to resolve the diplomatic dispute that has broken out between the two sides over the case, adding, "certain documents have been exchanged, which would help settle the issue".
Iranian media reported the tanker was due to be released on Tuesday evening, but a senior official has said the claims are "untrue".
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.
Two weeks after the ship's seizure, Iran's Revolutionary Guard Corps captured a UK-flagged, Sweden-owned, vessel for breaking "international maritime" rules in the Strait of Hormuz.
Tensions have Iran and the West have been rising since the Trump administration reimposed sanctions on Iran following its abandonment of the nuclear deal.
The grace-1 oil tanker was flying the Panama flag, but the government recently announced that it withdrew its flag from a number of Iranian-registered vessels.
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. Following the resumption of USA oil sanctions on Iran, some Iranian officials have warned that continued oil exports to other Gulf countries would be hard if Iranian oil exports were cut.
Israel has been striking Iranian targets in Syria over the past few years in an effort to limit the Islamic Republic's presence in its immediate neighborhood, and according to recent reports, has expanded those operations to hit Iranian-backed militias in Iraq.