Georgia's breakaway Abkhazia accused Tbilisi on Thursday of trying to suffocate the Black Sea territory and threatened a "proportionate response" to a Georgian blockade in which two ships have been seized this week.



Georgia has stepped up efforts to isolate Abkhazia and another breakaway region, South Ossetia, since a five-day war with Russia last August. It has banned economic and commercial activities there without its permission.



A tanker delivering fuel to Abkhazia was detained this week by Georgian authorities, and its Turkish captain remanded in custody. He faces up to 24 years in prison if found guilty of smuggling and violating the ban on unauthorised economic activity.



On Thursday, the Georgian coastguard said it had detained another vessel carrying scrap metal from Abkhazia. It was operating under a Cambodian flag with a Syrian crew.



Coastguard head Besik Shengelia said it was the fourth such seizure this year.



Abkhazia compared Georgian authorities to Somali pirates.



"Under the law in force in Georgia, we don't even have the right to breathe without permission from Tbilisi," Abkhazia's foreign minister, Sergei Shamba, told Russian Interfax.



"We warned Georgia that we can make a proportionate response, take the same kind of actions that the Georgian side allows itself," he said.



The fuel tanker, operating under a Panama flag with a Turkish and Azeri crew, was detained off the Georgian coast on Monday carrying 2,000 tonnes of petrol and 700 tonnes of diesel, worth $3-4 million, according to the tanker's Turkish operator.