A senior SNP figure has been criticised over an article which suggested the deaths of elderly people had contributed to an increase in support for independence.

Angus Robertson, the party’s former Westminster leader, made the comment in the context of more young people becoming eligible to vote and some older voters dying.

Scottish Tory leader Douglas Ross responded: “Disgraceful and deeply disappointing comments from Angus Robertson – suggesting that the most vulnerable age group, who have been hardest hit through the tragic loss of so many lives throughout the pandemic, are a boost to his independence obsession. A new low for the SNP.”

In an article for the National, the former Moray MP, who is trying to become an SNP candidate for Holyrood, addressed the issue of increased support for independence.

He wrote: “Since 2014, opinions have clearly not been static, and polls have shown a gradual rise in support for independence.

“This could be significant partly because of the underlying change in the electorate, with roughly 55,000 predominantly Yes supporting 16-year-olds joining the electorate and 55,000 predominantly No supporting older voters passing away every year.”

He added: “Since 2014, this has added around 330,000 voters to the electorate, with a likely net gain of over 100,000 for independence.”

However, Labour MSP Monica Lennon said: “The man tipped as a successor to Nicola Sturgeon thought this was ok. Not ok @Angus Robertson.”

Lib Dem health spokesman Alex Cole-Hamilton also described Robertson’s remarks as “really dark”.

Pamela Nash, chief executive of Scotland in Union, said:

“These are crass and deeply insensitive remarks, particularly at a time when so many in Scotland are mourning the deaths of loved ones.

Robertson defended himself: “I have two elderly parents and like everyone else want the best for them and all older people. I was presenting simple statistical facts about the support for independence amongst different generations in changing society.

“This manufactured outrage and attack on me is demonstrably politically motivated. Andy McIver, the former head of communications for the Scottish Tories, and I made exactly the same point in different articles on the same day. That Tories have only attacked me tells you everything you need to know.”