Piracy has made Somali waters among the world's most dangerous
A South Korean warship has caught up with a super-tanker that was hijacked by Somali pirates in the Indian Ocean.
The South Korean foreign ministry said the destroyer had arrived in waters near the tanker and would remain at a safe distance.
The 300,000-ton Samho Dream, which was on its way from Iraq to the United States, has 24 crew and is laden with crude oil.
Its owners said the pirates had not yet made any demands.
When the crew of the South Korean-operated super tanker first raised the alarm the navy destroyer, already on duty in the Gulf of Aden, was about 1,500 km (930 miles) south-east of the area where the hijacking took place.
It was ordered to close the gap at speed and has now reached the hijacked ship which is believed to be heading for the Somali coast.
The foreign ministry said that the frigate would continue to track the oil tanker from a safe distance.
The BBC's Korea correspondent John Sudworth says there appears to be no plans to intercept it.
He says that the estimated 1.5m barrels of oil on board is a very valuable, but also potentially volatile cargo.
Any attempt to apprehend it by force could put the crew of five South Koreans and 19 Filipinos in greater danger, and could cause severe environmental damage, correspondents said.
The destroyer is reportedly equipped with weapons that can hit targets about 32 km (20 miles) away and has a Lynx combat helicopter on board.
Pirates targeting ships off the coast of Somalia made tens of millions of dollars in ransom payments last year.
South Korea is one of several Asian nations to have added warships to Western-led anti-piracy patrols in Somali waters.
At least four South Korean ships have been hijacked by Somali pirates in recent years.
The first successful hijacking of a so-called Very Large Crude Carrier was of the Saudi-owned Sirius Star in late 2008.
Another VLCC, the Maran Centaurus, was taken last November and held for two months before a ransom estimated at between $5.5m and $7m was paid.