Lord Robertson, a former Labour defence secretary, will argue that the industry needs the “clout of a big global player”.
He will use a speech in his native island of Islay to speak out about the potential impact of a Yes vote in September’s referendum could have on the sector.
A Scottish Government spokesman argued leaving the UK would boost the whisky industry, as independence would provide an “unprecedented opportunity to showcase the Scottish brand internationally”.
But Lord Robertson will say: “As a native of Islay and a former trade union representative of the whisky workers, I know well how valuable whisky is to the local and national economy.
“It is the strength of the UK’s trade diplomacy which is so important to the industry. This strength is needed in the European Union, in the World Trade Organisation, and sometimes bi-laterally.”
He will add: “Many of Islay’s distilleries are owned by multinational companies who want to sell Scotch in hundreds of international markets.
“They know that in the ruthlessly competitive alcoholic spirits market they need the protection and promotion of the UK’s formidable network of embassies and diplomats.
“The success of the industry depends on being able to overcome trade barriers in important markets.
“It surely speaks volumes that no significant figure in the whisky industry or the trade unions who represent its employees has come out for a separate Scotland.
“The Scotch whisky industry will - more than any other - need the clout of a big global player. The breakup of Britain would be very bad news for this Scottish success story.”
But a Scottish Government spokesman said: “Scotland’s whisky industry is booming around the world, thanks to the hard work of everyone in the sector and the quality of the product, and is a shining example of how Scotland can succeed on the global stage.
“Whisky is part of a hugely successful and still growing food and drink sector - and independence will provide an unprecedented opportunity to showcase the Scottish brand internationally.
“But the UK’s planned in-out referendum on EU membership threatens our food and drink industry’s current access to Europe’s single market of 500 million citizens and 20 million businesses - and only a vote for independence will secure our place in Europe.”