Scottish pro-independence parties reported a surge in membership over the weekend as campaigners vowed to continue to fight after a split with the United Kingdom was rejected in a referendum.

The Scottish National Party said its servers were struggling to cope with 11,000 new membership requests in the 75 hours following the referendum on Thursday, when it had 25,600 members.

The SNP's leader Alex Salmond announced he would step down as Scottish first minister after 55 percent of voters rejected independence, and British Prime Minister David Cameron said the question had been settled for a lifetime.

However, supporters of independence vowed to continue their campaign on social media, many including the figure "45" in their profile pictures to represent the percentage that voted for the split.

"As a former Labour councilor of 15 years, I have today joined the SNP," said pro-independence aviation consultant John Baillie on Twitter. Baillie was previously the Labour Party leader on South Ayrshire Council.

"On Friday, I mainly felt angry. Yesterday, I just felt sad. Today, I joined the SNP. Never give up on what you believe in," a Twitter post said on Sunday.

The pro-independence Scottish Green Party said its membership has increased by 2,000 since Thursday.

The referendum campaign has seen a huge rise in engagement in politics, and a turnout of 84.5 percent, and more than 90 percent in some areas, broke previous records in Britain.