UK Foreign Secretary Jeremy Hunt confirmed on Saturday that British tanker Stena Impero has been seized by Iran "in clear contravention of international law", but reaffirmed his country's desire to de-escalate.

He made the remarks on his Twitter account after government emergency committee met on Saturday afternoon, discussing on how to secure the safety of UK and international shipping in the Strait of Hormuz.

Hunt added that the UK Parliament will be updated on Monday.

In his earlier tweets on Saturday, Hunt said he just spoke with Iranian Foreign Minister Mohammed Javad Zarif and "expressed disappointment" that having assured the UK last Saturday that Iran wanted to de-escalate the situation, "they have behaved in the opposite way."

"This has to be about actions not words if we are to find a way through. British shipping must & will be protected," he added.

Following Iran's seizure of Stena Impero, a British-flagged vessel, in the Strait of Hormuz, Hunt said the move "shows worrying signs that Iran may be choosing a dangerous path of illegal and destabilizing behavior after Gibraltar's LEGAL detention of oil bound for Syria."

"We have been trying to find a way to resolve Grace 1 issue but WILL ensure the safety of our shipping," he added.

The police of Gibraltar, which is seen by Britain as its overseas territory, arrested last week the captain and chief officer of an Iranian oil supertanker Grace 1 after intercepting it on July 4 in the Strait of Gibraltar on suspicion of transporting Iranian crude oil to Syria, in violation of the European Union's sanctions against Syria.

The Iranian foreign minister met UN Secretary General Antonio Guterres in New York on Thursday and discussed "the tension in the region, the UK's illegal seizure of a tanker carrying Iranian oil, and Iran's reduction of its nuclear commitments" among other issues, according to the Iranian Foreign Ministry.

"As I said in NY, it is IRAN that guarantees the security of the Persian Gulf & the Strait of Hormuz. UK must cease being an accessory to #EconomicTerrorism of the US," Zarif noted on Saturday in a tweet.