Iran’s former charge d’affaires to the UK Seyyed Jalal Sadatian said that before the release of the oil tanker, my prediction was that Britain would have to release the tanker because it had no good excuse.
Speaking to ILNA news agency, he added "They found out that the seizure of an Iranian oil tanker was not legal."
"The Grace 1 vessel could cross the Suez Canal to enter Syria, but crossing Gibraltar indicated that its destination was different and there was no document to indicate the destination of Iran oil tanker."
Iran denied the tanker was bound for Syria and threatened to seize a British oil tanker in retaliation.
Answering to question about The United States and the United Kingdom will be looking for close relations when Britain leaves the European Union, so London increases its pressure on Iran, Iran ex-diplomat said "London has inevitably turned toward Washington and tends to bolster the transatlantic aspect."
"Some analysts say the British Prime Minister Boris Johnson thought that he could use this subject as a tool to bolster his sovereignty but he failed to open a new front," Sadatian added.
The Grace 1 vessel, which was ordered to be released by the Gibraltar Supreme Court after 43 days in detention, shifted position but remained anchored in the British Mediterranean territory late on Friday.
The United States has issued a warrant for the seizure of an Iranian oil tanker captured by British Royal Marines in Gibraltar last month for allegedly violating international sanctions.
Earlier on Friday, Iranian officials said the tanker was preparing to set sail under an Iranian flag after its registration was switched from Panama and would be renamed the Adrian Darya for the voyage.
Iran called the detention of the Grace 1 an "illegal interception" staged by the US, while Washington cheered it as "excellent news".