The representative said: "We are very confident we will raise the funds. Securing funding for the next 10-year period is well into the planning stages. We need to increase the speed at which we collect species, as plants are dying out at a faster rate. And we can start to use the seed stored for reintroductions where wild species have died out."
The Foundation & Friends of Royal Botanic Gardens, Kew is responsible for the fundraising and is targeting corporate sponsors and individuals rather than campaigning for government money.
The MSB representative added that a seed vault that opened in the Arctic last week is not a threat to the future of the MSB. "The Svalbard Global Seed Vault is actually a back-up for gene banks across the world. The team there is focusing on food crops while we concentrate on wild plants."
The MSB - run by the Royal Botanic Gardens, Kew at Wakehurst Place, West Sussex - is the largest wild plant seed bank in the world. It already stores 96 per cent of the UK's flora and aims to have collected seed from 10 per cent of the world's wild flowering plant species by 2010.
The first deposits in the Svalbard vault, which opened last Tuesday, were seeds of food crops, but the facility has the capacity to store 4.5 million seed samples, equivalent to about two billion seeds.