More than 11,000 people set up fundraising pages for this year's London Marathon on the new Virgin Money Giving website.
A Virgin spokesman said 9,279 of the new pages were used for donations and the rest were inactive. Between £5m and £7m had been raised on the site so far, he said, and a total would be provided in the next few weeks.
A spokeswoman for Virgin Money Giving's main rival, the long-established JustGiving, said it had 20,872 London Marathon pages this year, 847 fewer than last year; 15,011 of these pages were active. More than £19.5m had been donated on the site to support London Marathon runners so far this year, she said; the average per page was up 4.5 per cent on last year's figure, at £1,308.
The Virgin site was launched in October last year after it was announced that Virgin would take over sponsorship of the marathon from Flora. The London Marathon website describes Virgin Money Giving as "the official fundraising website for the Virgin London Marathon".
The Virgin spokesman said marketing for the marathon and the website had been "entwined". He said there were 1,500 more runners in this year's marathon than in last year's, which partly explained the increase in the overall number of people setting up fundraising pages online.
The increase might also have been caused by a shift away from smaller fundraising sites, or by people choosing to raise money online for the first time, he said.
The spokeswoman for JustGiving said she expected this year's fundraising total on the site to be close to last year's figure of £25m. She said integrating JustGiving with social networking site Facebook had encouraged runners to use the site.