FEARS have been raised that Scotland’s coastline faces contamination from exotic foreign species amid alleged weaknesses in controlling dispersal of ballast water from ships.

The UK has been condemned as the only nation bordering the North Sea that has failed to ratify an international agreement which would safeguard Scotland’s waterways.

Britain’s signature alone could usher in a new era of protection for marine life but Whitehall’s perceived procrastination over signing the International Maritime Organisation’s (IMO) new convention on ballast water control, means weaker measures remain in place, it has been claimed.

Conservationists say the UK’s failure to agree the measure lies in its support for ship to ship oil transfers, such as those controversially proposed for the Cromarty Firth.

The fear is that harmful non-native species, bacteria and pathogens are carried by tankers in untreated ballast water, which they then discharge approaching port.

Dr Richard Dixon, Director of Friends of the Earth Scotland said it was “ a disgrace that the UK is dragging its heals on this”.

He said: “There can be no doubt that the failure to ratify this convention is related to the UK government’s enthusiasm for the risky practice of ship-to-ship oil transfer.”

According to National Geographic, which campaigns on the issue, hitchhiking species had be harboured within 45,000-tonne tankers moving more than 10 billion tons of ballast water around the world each year.

The magazine cites one “infamous example” in which the zebra mussel was accidentally introduced by a cargo ship into the North American Great Lakes from the Black Sea in 1988.

They multiplied uncontrollably, starving out many of the Great Lakes’ native mussel populations and had interfered with human activity from factory intake pipes to ships’ rudders.

They spread from Canada to Mexico and “hundreds of millions of dollars are spent annually to control their numbers”.

The new IMO convention would require ships to treat ballast water before it is discharged, where currently IMO rules only state that a ship should change ballast water during its journey.

News of the UK’s failure to sign the agreement was highlighted by Highland community group Cromarty Rising which is campaigning against plans for nine million tonnes of crude oil to be transferred annually between tankers lying at anchor at the mouth of the Cromarty Firth.

France, Germany, the Netherlands, Belgium, Denmark and Norway have already ratified the new IMO Convention since 2004.

A spokesman for the Environment Secretary, Roseanna Cunningham, said: “The UK government, which retains control over this issue, must act to ensure Scotland’s seas receive the level of protection they need.”

The UK Department for Transport was asked to respond, but passed to the MCA, who said the UK fully supported the aims of the convention, but added: “The UK has not ratified the Convention while the IMO continues to work on outstanding matters concerning sampling, analysis and testing of ballast water and the method of approval for treatment systems. Legal clarity on these points is necessary before the UK can progress ratification.

“We are confident that the efforts at the IMO will address these concerns.”