SCOTLAND's 17,000 postal workers are to be urged by their union to vote against independence after a motion was passed at the main union's annual conference.

Better Together hailed the result of the ballot at the annual conference of the Communication Workers Union (CWU), pointing out it was the sixth major trade union in Scotland to "back Scotland's place in the UK."

But Yes Scotland pointed to the Scottish Trades Union Congress (STUC), which is not supporting the pro-UK campaign.

The CWU decision was taken after a motion recommended a No vote to its Scottish membership at the event in Bournemouth.

The union's took soundings via a series of meetings and two polls of members at the event, which was attended by about 800 delegates. They showed 60 per cent support among its Scottish members against the SNP policy.

CWU General secretary Billy Hayes said: "This decision is based on a need for unity against austerity and the barrage of cuts from the coalition Government and the SNP in Scotland.

"This is an extremely important constitutional debate and it is crucial that as a trade union we are able to assist our members on the impact this will have on the Scottish economy and that of the rest of the UK.

His deputy Andy Kerr said the union believes independence would have a "profound effect" on companies it works with, including Royal Mail, the Post Office and BT. He said they have extensive networks operating in Scotland and independence would put "untold pressure" on the firms and their members working lives.

Mr Kerr added: "It's not clear what the implications would be on Royal Mail's Universal Service Obligation in an independent Scotland, the pension schemes our members are enrolled in or how it would affect the roll-out of broadband services to the inaccessible rural communities in Scotland.

"Independence would have a significant impact on the ability of these companies to invest in their networks."

Shadow Scottish Secretary Margaret Curran said: "A vote for Scotland to remain in the UK is a vote for the trade union way - working together with family, friends and colleagues across the whole of the UK to make Scotland a fairer place to live. I am delighted that posties will be working hard to deliver a No vote in September."

Blair Jenkins, chief executive of Yes Scotland, said individual unions representing tens of thousands of workers have already agreed support the STUC line.

He said: "However, it should be emphasised that the STUC's ­position is that it is 'more attracted' to Yes. It is our job and intention between now and September 18 to persuade all trade unionists of the opportunities of Yes to build a fairer and more socially just Scotland, to protect and enhance workers' rights and to create new jobs by growing our economy in a responsible and sustainable way."