Iran has defended its move in capturing a British tanker in the Persian Gulf, saying that the vessel was impounded after it breached international law by attempting to flee the scene of a dangerous collision with an Iranian boat.

In the letter on Wednesday, Iran told the United Nations Security Council that the British tanker "Stena Impero" collided with a small fishing boat on July 19, and badly injured its crew -- some of whom remain in critical condition.

Afterwards, instead of responding to distress calls from the boat and radio communications from Iranian authorities, the British tanker turned off its transponder and "dangerously" changed course in the direction of incoming ships, the letter read.

That is when, according to the letter, Iran's Islamic Revolution Guards Corps (IRGC) intervened and took the ship and its crew into custody.

Tehran asserted in the letter that the seizure, which took place in accordance with international regulations, was necessary for protecting the safety and the order of maritime navigation at the Strait of Hormuz strategic choke point.

According to the letter, Iranian judicial authorities had ordered local officials to investigate the tanker's violations, including its environmental damage as well as the extent of the damage it has done to the fishing boat and its crew.

The letter also rejected claims by the UK government in a recent letter to the UNSC, where it had claimed the IRGC forces acted illegally by approaching the Stena Impero in " Omani territorial waters."

Iran's permanent mission at the UN said in its letter that everything it did was aimed at upholding international law and ensuring secure navigation in the Persian Gulf.

Iran warns UK against causing 'dangerous confrontations'

Meanwhile, Brigadier General Hossein Dehqan , a top military advisor to Leader of the Islamic Revolution Ayatollah Seyyed Ali Khamenei, warned the UK about the possible ramifications of its calls for a European force to escort tankers in the Strait of Hormuz.

"The UK's proposal for a European force in the Strait of Hormuz could lead to unpredictable consequences [for London]," General Dehqan told Al jazeera on Wednesday. "Our equation in the Strait of Hormuz is that either everyone enjoys full security or no one does."

Tensions between Iran and the UK began earlier this month, when British naval forces seized an Iranian oil tanker in Gibraltar under the pretext that it was carrying oil to Syria in violation of European Union sanctions against the Arab country. Iran has denied the claim.