The government of Gibraltar has confirmed the detained VLCC Grace 1 is carrying a full cargo of crude.
The oil on the 301,000-dwt tanker (built 1997) was tested "comprehensively" in a laboratory, it added.
The tanker was detained last week when "it freely navigated into British Gibraltar territorial waters (BGTW) to a point two miles off the east of the rock, having previously exited the international waters of the Straits of Gibraltar, on a pre-arranged call for provisions and spare parts," the government said in a statement.
