Tasnim � Iranian Ambassador to London Hamid Baeidinejad said the country will take legal action against a British court ruling on a series of defense deals signed between the two countries before the 1979 Islamic Revolution.

A top court in Britain has dismissed a complaint lodged by Iran seeking at least �20 million in interest for a debt related to the defense deals. Judge Stephen Phillips from the High Court in London ruled on Friday that the UK does not have to pay the sum that Iran believes has accrued on �387 million owed to Tehran over the failed delivery of more than 1,500 Chieftain tanks and armored vehicles based on contracts signed as of 1971.

In a post on his twitter account late on Friday, Baeidinejad said, �The Islamic Republic of Iran disagrees with the UK court�s decision not to require the British company to pay part of the interest of its debt in the years of sanctions and will take the necessary legal action.�

�However, this ruling has no effect on the obligation of the British company to pay in full the several hundred million pounds of debt and its interest for over 30 years,� he added.

The ruling deals a fresh blow to efforts meant to reduce tensions between Iran and Britain as the two countries are locked in several disputes, including two recent ship seizure incidents and a high-profile legal case related to the imprisonment of dual nationals.

Britain has repeatedly refrained from paying the debt it acknowledges it owes to Iran, citing illegal sanctions imposed by the United States on Tehran.

Newly-appointed Prime Minister Boris Johnson once briefed the journalists in February 2018 after a trip to Tehran as foreign minister that the money will be paid back.

However, the payment never took place to the irritation of Tehran which thinks London is trying to use the case to solve other problems, including the much-publicized imprisonment of Nazanin Zaghari Ratcliffe, an Iranian-British national who is in jail in Iran for espionage convictions.

The court ruling also comes amid renewed tensions in the Persian Gulf where Iran has refused to release a British tanker since it was seized last Friday for violation of maritime rules.

The incident came two weeks after British marine forces boarded a supertanker laden with Iranian oil near the coast of Gibraltar.