MADRID, July 11 (Xinhua) -- Gibraltar police arrested the captain and chief officer of an oil supertanker Grace 1 on Thursday, the Gibraltar Chronicle reported, quoting official sources.

According to the British authorities, Grace 1 aims to transport Iranian crude oil to Syria, which the United Kingdom considers a violation of the European Union's sanctions against Syria. The tanker ship was first intercepted by British Marines and Gibraltar police in the Strait of Gibraltar in the south of the Iberian Peninsula on July 4.

A spokesperson of Gibraltar police said that the two men arrested were being investigated but have not been charged yet. Documents and electronic devices were also seized from the tanker.

According to RT news, Grace 1 is owned by a Singaporean company and flies a Panama flag. Local authorities said they had obtained an order from Gibraltar's Supreme Court to extend the detention of Grace 1 for 14 days for violating the sanctions imposed on Syria.