Proposals to set up a rival freight service could mean millions of pounds worth of lost business for the company which is set to take over the lifeline ferry link to Orkney and Shetland.

NorthLink - a joint venture between Caledonian MacBrayne and the Royal Bank of Scotland - will start running the route on 1 October.

The company won the five-year contract, which carries a public subsidy of £11m, ahead of P&O Scottish Ferries - which has operated the service for more than 30 years.

We still think that we will be able to compete

John Norton NorthLink

It promised more frequent sailings, shorter journey times and cheaper fares on the routes from Scrabster to Orkney and Aberdeen to Orkney and Shetland.

However, BBC Scotland has learned that the three biggest haulage companies in the Northern Isles are setting up an alternative freight service because they are unhappy with the new charges.

The move could cost NorthLink millions of pounds worth of business.

Northwards, JBT Transport and Shetland Transport carry more than 80% of the freight on the existing route.

They spend more than £8m a year shipping goods.

'Surprised and concerned'

The companies have signed a preliminary agreement to set up a new ferry operating company to provide a daily freight service to Shetland.

NorthLink said it was both surprised and concerned by the move.

Chief executive John Norton said: "We still think that we will be able to compete and we will still bring the service in and we will compete effectively."

Tavish Scott: "Too short a time:

However, the issue is only the latest problem to affect the introduction of the new service.

One of the new vessels which will sail on the route will not be ready in time - and neither will a pier at Scrabster on the Scottish mainland.

A proposal to run the service from Orkney to Aberdeen until this pier is completed has been mooted, but this would increase journey times from two to seven hours.

Such a step was described as "totally unacceptable" by Councillor Jim Sinclair, the vice convener of Orkney Islands Council.

He said a solution had to be found which would provide a link between Stromness and the Caithness coast.

Difficult transfer

Tavish Scott, the Liberal Democrat MSP for Shetland, said the Scottish Executive had to learn lessons from the whole tendering process.

"It has been pulled up into much too short a time period," he said.

"That has put a huge amount of pressure on the operators in terms of that transfer, which was inevitably going to be difficult."

A Scottish Executive spokesperson said it recognised that there were a number of difficulties in delivering a new ferry service to the Northern Isles.