Despite being escorted by a British warship, the oil tanker was stopped on Friday by Iran and was led to the coastal harbour for a legal investigation, Xinhua news agency reported Iran's IRNA news agency as saying.
The tanker has crew members of Indian, Russian, Latvian and Filipino nationalities aboard.
Iran's Islamic Revolution Guard Corps (IRGC) seized the British oil tanker in the Strait of Hormuz for what it called "failing to respect the international maritime rules while passing through the strait."
The spokesman for the IRGC has condemned the British oil tanker's action on Saturday, saying there was a risk of collision because of the tanker's wrong direction, adding that Iran is acting legally and within the bounds of its national sovereignty in the Gulf and the Strait of Hormuz.
British Foreign Secretary Jeremy Hunt said on Saturday via Twitter that he had spoken to Iranian Foreign Minister Mohammad Javad Zarif and "expressed extreme disappointment" that while the Iranian diplomat had assured him Iran wanted to de-escalate the situation, "they have behaved in the opposite way."
"Our reaction will be considered but robust," said the British official.
Hunt's words was echoed by British Defence Minister Tobias Ellwood on Sunday, who said that his country is looking into a series of options to respond to Iran's seizure of the British tanker.
"Our first and most important responsibility is to make sure that we get a solution to the issue to do with the current ship, make sure other British-flagged ships are safe to operate in these waters and then look at the wider picture," Ellwood was quoted by Sky News as saying.
Iran's Ambassador to Britain Hamid Baeidinejad on Sunday tweeted that London should contain those "domestic political forces" which he said wanted to escalate tension between the two countries well beyond the issue of ships.
"Iran, however, is firm and ready for different scenarios," he added.
( With inputs from IANS )