Roger Kohn, spokesman for the International Maritime Organisation (IMO), confirmed that the waters around the Shetland Isles were classified as 'an area to be avoided'.
International Collision Regulations say a 10-mile protection zone is necessary to 'avoid the risk of oil pollution and severe damage to the environment and the economy of Shetland'. The regulations stipulate that all shipping of more than 5,000 gross tonnes should avoid the area.
Two years ago the IMO gave the zone legal sanction - which means that if a vessel travels within the area it can be prosecuted. Yesterday, the Department of Transport said the tanker ran into difficulty '10 miles off the Sumburgh point', and that it was too early to say whether a prosecution was in the offing.
A spokesman emphasised that the weather was extremely bad, so the ship could have been within a mile or two either side of the protection zone.
The captain's responsibility was to his ship and crew first, the spokesman said - then to the environment.
Paul Roberts, European representative of Oceanroutes, which advises the shipping industry on weather conditions along prime trading routes, said oil tankers did not have standard routes.
'They go all over the place. From Norway it is fairly natural for tankers to go around the top of Britain. If conditions are horrendous we might recommend the Channel, but extra miles means extra days means lots of bucks.'
Mr Roberts said often ships' crews had no idea of weather conditions before they hit them. If they were to change route to avoid adverse conditions they could run into something worse.
The problem is that crews often rely on three-day forecasts rather than buying in the longer 10-day forecasts available. If they depend on these shorter predictions they are virtually committed to a route as soon as they leave port.
Mr Roberts said that might have happened with the Braer yesterday. 'Three days out they would be approaching the north of Britain and facing the full fury of whatever's in the Atlantic - of which they probably did not have a bloody clue.'
The tanker was a single-hulled vessel, a design frowned upon by ship safety experts. In 1989, the Exxon Valdez disaster prompted US legislation that decreed that all new tankers visiting US ports must have a double hull, providing an extra layer of protection in collisions.
Joe Nichols, technical manager at the International Tanker Owners Pollution Federation, said yesterday that most ships afloat today were still single-hulled. 'People need oil, and you cannot do these things overnight. I don't think anybody can afford to be that choosy. If you have the oil, you also have the attendant risks.'
He said that a double-hull would not necessarily have prevented the Braer disaster. Once a tanker runs into rocks it is bound to be damaged seriously, putting its cargo at threat. 'It wouldn't have made any difference in this case, or in the Exxon Valdez either.' The US legislation was really aimed at future shipping, he said.
Last February, a report by the House of Lords select committee on science and technology pointed to newer ship designs such as double-hulled vessels when seeking ways to make shipping safer, both for crews and for the environment.
'In the event of a gentle grounding, such as happened to the Exxon Valdez, or a minor collision, the damage is less likely to penetrate the cargo spaces and cause pollution than if the hull were single,' the report said.
But double-hulled vessels present their own problems, Mr Nichols said. The space between the two hulls was prone to a build-up of dangerous gases, and possible explosions.
'The US legislation was a knee-jerk reaction to Exxon Valdez,' he said. He also pointed out that other designs might yet prove superior. One, known as the 'mid-deck' design, relies on water pressure from outside keeping most of the oil cargo in the hold. A European consortium is working on another tanker design, known as the E3 - Ecological, Economical and European - again a double-hull approach.
The Lords report called for an independent safety authority to replace regulation by a government department. 'The Lords want the department to hand ship safety regulation over to a Civil Maritime Authority, modelled on the CAA (Civil Aviation Authority).' The Government appears to have ignored this recommendation.
The committee warned ministers that 'the world regime for ship safety is unscientific and fragmented'. It urged ministers 'not to wait for another Herald of Free Enterprise' before handing over more resources for ship safety.
Last year's Lords report acknowledged that ship safety was improving.
'There is a new emphasis on the human element as well as the hardware, and on the reponsibility of shore-based management as well as the master; a new mood of urgency at the IMO, spurred by recent threats by some members to break ranks and impose safety standards unilaterally if the IMO cannot achieve consensus; and an increasing determination among port states of the developed world to keep out the 'substandard ship'. 'Reuse content