Iran on Thursday condemned what it said was the "illegal interception" of one of its oil tankers in Gibraltar which authorities suspect was carrying crude to Syria in violation of EU sanctions, AFP reports. The Islamic Republic announced it had summoned the British ambassador in protest. "After the illegal interception of an Iranian oil tanker in the strait of Gibraltar by the English naval force, that country's ambassador to Tehran was summoned to the foreign ministry," the ministry's spokesman Abbas Moussavi said in Tehran. The supertanker Grace 1 was detained on suspicion that it was carrying crude oil to Syria in what may be the first such interception under EU sanctions. Mapping indicates the Grace 1 loaded Iranian crude oil on April 17, and if this were confirmed, the attempted delivery to Syria could also be a violation of US sanctions on Iranian oil exports. The ship was detained 2.5 miles (four kilometers) south of Gibraltar in what it considers British waters, although Spain, which lays claim to the territory, says they are Spanish. It was boarded when it slowed down in a designated area used by shipping agencies to ferry goods to vessels. The incident comes at a sensitive time in Iran-EU ties as the bloc mulls how to respond to Tehran announcing it will breach the maximum uranium enrichment level it agreed to in a 2015 nuclear deal. The US left the 2015 nuclear deal last year, and Iran has been pushing the deal's remaining partners -- Britain, China, France, Germany and Russia – to help it circumvent US sanctions, especially to sell its oil. Its latest announcements on breaching the nuclear deal follow a meeting last Friday with European, Russian and Chinese officials to discuss ways to save the 2015 nuclear following the US withdrawal. Iran’s envoy to the meeting in Vienna said that European countries had offered too little to persuade Tehran to back off from its plans to breach limits imposed by the deal. The EU earlier this year introduced a trade mechanism that would bypass US sanctions on Iran, in a bid to save the 2015 deal, but Iran has rejected that mechanism thus far. Meanwhile on Thursday, White House National Security Advisor John Bolton applauded the interception of the supertanker in Gibraltar. "Excellent news: UK has detained the supertanker Grace I laden with Iranian oil bound for Syria in violation of EU sanctions," Bolton tweeted. “America & our allies will continue to prevent regimes in Tehran & Damascus from profiting off this illicit trade,” he added.