British Royal Marines seized the Iranian oil tanker on July 4 off the coast of the British Mediterranean territory of Gibraltar on suspicion of violating European Union sanctions by taking oil to Syria, which Tehran denies.
Quoting Gibraltar authorities, the semi-official FARS news agency said the ship will be released by Tuesday evening.
Oil supertanker Grace 1 on suspicion of being carrying Iranian crude oil to Syria is seen near Gibraltar, Spain in this picture obtained from social media, July 4, 2019.
A senior Iranian maritime official says Britain may soon release an Iranian oil tanker that was seized last month off the British Mediterranean territory of Gibraltar.
"The vessel was seized based on false allegations ... it has not been freed yet", Eslami said.
He noted that Iranian vessels, both oil tankers and merchant ships, are commuting under normal conditions in worldwide waters despite some difficulties.More news: Serena Williams in Rogers Cup semis
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"The investigations being conducted around the Grace 1 are a matter for the government of Gibraltar", a British Foreign Office spokesman said.
Mr Eslami said: "Efforts from Iran and the port organisation have been made for the release of this ship". The current detention order on the vessel expires on Saturday night.
Shortly after the incident Iran captured the British-flagged Stena Impero in the strategic Strait of Hormuz for breaking "international maritime rules".
On August 6, Israeli regime's Foreign Minister Israel Katz said that they will be part of the US-led anti-Iran coalition.
"We remain committed to working with Iran and our global partners to de-escalate the situation and maintain the nuclear deal".
Tehran rejected London's claim that the tanker was heading to Syria, slamming the seizure as "maritime piracy".