A protest has been held over claims Northern Isles ferry crew members are being paid less than the minimum wage.

Foreign seafarers sailing on ferries contracted by the Scottish Government earn as little as £4 an hour, the RMT union has said.

Seatruck insists this is legal and has rejected offers to help it cover the cost of paying the basic rate.

Speaking during the protest in Aberdeen on Friday, RMT regional organiser Gordon Martin said: "We're here today because of the ship of shame - the Seastruck vessel on the Scottish Government contract - is paying below the national minimum wage, way below the living wage, and exploiting foreign workers.

"This is a government contract so surely if Seatruck are not paying what the government believes to be an acceptable rate of pay the contract should be null and void."

RMT members held a demonstration at Aberdeen harbour on Friday morning, before moving to the offices of local SNP MP Callum McCaig and MSP Maureen Watt.

A spokesman for the Scottish Government said: "The Scottish Government is deeply disappointed that Seatruck has once again rejected Serco's offer to pay their staff the minimum wage and backdate this.

"Scottish ministers are working with stakeholders on the next Northern Isles Ferry Service contract.

"Work is being done to ensure that any future subcontractors pay the minimum wage, regardless of where the company or crew are based."

Northlink, which sub-contracted the ferry route between Aberdeen and Shetland to Seatruck, said it has repeatedly offered to cover the cost of paying the basic rate of £6.70 an hour.

A spokesman said: "We have been trying to address the issue with Seatruck since 2014 and have repeatedly made offers to pay them an amount that would fully cover the additional cost of paying the UK minimum wage. Seatruck have refused to accept this offer."

Seatruck claims that paying Northern Isles crews the minimum would "distort its fleet-wide pay structure".

A spokesman for the firm said: "Under current legislation the UK national minimum wage is not applicable to crews of the Helliar and Hildasay, as they are not deemed to be 'ordinarily working in the UK'.

"They start and finish their tours of duty in their home countries, they are working on non-UK flagged vessels, they are not resident in the UK and they do not pay tax or national insurance in the UK."