The pro-Union Better Together campaign group has received £1.6 million in donations since April this year, it has been revealed.

Figures published by the group showed the biggest donor, Argyll businessman Donald Houston, gave £100,000 plus £500,000 through two of his companies.

Investment banker Andrew Fraser gave £200,000 and Alan Savage, chairman of Inverness-based recruitment group Orion, gave £150,000. Author Christopher Sansom donated £133,000.

Since April more than 17,000 people have ­given to the campaign, mostly giving sums less than £500.

The group has received almost £2.8 million since it was established in May 2012.

Among donors listed this year are former banker and Arsenal chairman Sir ­Chippendale Keswick, who gave £23,000.

Mr Houston, director of the Adelphi Distillery in Ardnamurchan, said: "We have spent 300 years building a union between our ­countries that has achieved so much. Ripping up that union to satisfy the SNP is a ridiculous idea.

"The people of the Highlands that I speak with consider the SNP government in Edinburgh to be completely remote from our opinions and our way of life."

Mr Savage said: "My support for the Better Together campaign is stronger than ever following the publication of a White Paper that does nothing to convince me that independence would be a force for good for Scotland."

Better Together director Blair McDougall said the group was "humbled" by the donations.

"Thousands of people are playing their part in keeping Scotland a strong part of the United Kingdom," he said.

The SNP said the identity of Better Together donors highlighted the campaign's "Tory roots". Angus Robertson MP said: "No wonder …Labour supporters and grassroots members are turning their backs on the No camp."

The Yes Campaign backing independence is to publish further details of cash it has received in due course.

"It continues to be our policy to accept significant donations only from people who are entitled to vote in the referendum," said a spokesman.