A tanker carrying up to 90,000 tonnes of crude oil has spilled some of its cargo en route to Milford Haven in Pembrokeshire, west Wales.

Coastguards report only a small volume of oil has entered the haven from the vessel, the 1992-built Norwegian-registered Magnitude.

More than 1,000 people helped in the 1996 spill

Milford Haven is a major port for vessels shipping oil to Britain.

In February 1996 Wales suffered its worst environmental disaster in decades when the tanker Sea Empress ran aground, spilling 72,000 tonnes of crude oil into the estuary.

The Maritime and Coastguard Agency (MCA) said the Magnitude was 20 miles off Milford when a sheen was spotted around the stern of the vessel on Sunday.

The cargo was being transferred from one tank to another inside the vessel.

A spotter aircraft was sent to fly over the area and it appears the leak has stopped.

Leakages

The MCA is tracking the vessel which is due into Milford on Friday.

A spokesman said it was not uncommon for ships to leak but obviously they were concerned and were monitoring the situation.

Milford Haven coastguards said they were first alerted at 1344 GMT on Monday, after the ship's owners contacted them.

The coastguards launched their counter pollution branch, whose Atlantic 404 "sniffer" aircraft carried out a fly-over.

The plane has remote sensors capable of detecting any leakages beneath the sea's surface - but in this case found nothing.

Sea birds

The Sea Empress oil spill was the third-largest tanker spill in UK waters after the Torrey Canyon, off Cornwall in 1967, and the Braer, off Shetland in 1993.

Around 120 miles of coastline were polluted in the Haven and between Cardigan Bay and Pendine Sands, including the holiday resorts of Tenby and Saundersfoot.

Tens of thousands of sea birds were killed by the oil pollution and more than 1,000 people were involved in the clean-up.

An official inquiry partly blamed the inadequate training and inexperience of a port authority pilot who had never before handled such a big vessel close to low tide.