Gibraltar has refused a request by the United States to seize an Iranian oil tanker at the centre of a diplomatic standoff between Tehran and Europe.
British Royal Marines had seized the vessel in Gibraltar in July on suspicion that it was carrying oil to Syria, a close ally of Iran, in violation of European Union sanctions.
That detention ended last week, but on Friday a US court issued a warrant for the seizure of the tanker, on the grounds that it had links to Iran's Islamic Revolutionary Guard Corps (IRGC), which Washington has designated a "terrorist" organisation.
Gibraltar's government said on Sunday it could not comply with the US request because of European law.
"The Central Authority's inability to seek the Orders requested is a result of the operation of European Union law and the differences in the sanctions regimes applicable to Iran in the EU and the US," the government said in a statement.
"The EU sanctions regime against Iran - which is applicable in Gibraltar - is much narrower than that applicable in the US."
Iran has denied the tanker was ever headed to Syria.
Al Jazeera's Andrew Simmons reporting from Gibraltar said he doesn't expect the situation to change despite the issue of the detention order, and the later rejection of it.
Tehran said on Sunday it was ready to dispatch its naval fleet to escort the tanker - now renamed the 'Adrian Darya-1' - if required.
The seizure triggered a sharp deterioration in relations between Iran and the United Kingdom. Tehran subsequently detained the British-flagged tanker. That tanker, the Stena Impero, is still detained.